Category: Lifestyle

Sleep loss and exercise performance – Episode 52 with Dr Michael Grandner


No doubt, you are well aware that a bad night’s sleep can leave you struggling for energy and the ability to remain alert. But did you know that sleep loss and exercise performance also have a strong connection! Even small amounts of lost sleep that become a regular habit can have a significant negative impact on your sporting performance, your exercise and, ultimately, your fitness results. Episode 52, with a global leader in the field sleep research, Dr Michael Grandner, will help unfold the details and give you actionable tips to help restore your sleep today!

Guest Biography

Dr. Michael Grandner is the Director of the Sleep and Health Research Program and Associate Professor, Clinical Translational Sciences, Medicine, Psychiatry, and Psychology in the University of Arizona College of Medicine – Tucson. He is Board-Certified in Behavioral Sleep Medicine. Dr Grandner has 4 university degrees, obtaining his PhD in clinical psychology 2007. He has published 100’s of scientific articles and been cited 1000’s times across the scientific literature and is one of the leading voices in the field of sleep science. Several of his published journal articles directly address the impact of sleep, or lack of sleep, in relation to sporting performance. Dr Grandner served on the Olympic Mental health consensus committee where they published an official Olympic statement calling for greater awareness of mental health for elite athletes. He recently served as lead editor for an outstanding book titled, Sleep and Health (2019), which will serve as an influential text in the field of sleep for years to come. Find out more on Dr Grandner’s website.

Dr Michael Grandner

Episode content: Sleep loss and exercise performance

There was not enough time to ask everything we had hoped to cover in this fascinating dive into sleep loss and exercise, chronotype, and the impact on athletic and physical performance. Key topics and questions were:

  • 2:55  What led Dr Grandner into the field of sleep research
  • 6:50  Is chronotype and circadian phenotype the same thing?
  • 14.09  How can the listener determine their own chronotype?
  • 15:36  Do all individuals experience peak physical performance between 4-7pm?
  • 19:28  Is early morning exercise the least effective time to do exercise for all chronotypes?
  • 28:00  How can temperate regions work around the lack of early sunlight exposure during darker winter months?
  • 29:38  How can coaches and fitness trainers use the knowledge of chronotype variation to plan their client’s training schedules?
  • 33:44  The scope of sleep problems among elite athletic populations
  • 41:28  Does the science actually show that increasing the length of sleep has a positive impact on physical performance?
  • 46:16  Three evidence-based sleep tips that have been effective in demonstrating improvement for physical performance

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To enjoy more engaging expert interviews on the Fit to Succeed show, visit our podcast library.

Episode links

Re-timer light glasses

Online quiz to determine your own chronotype

workplace -wellness-for-highly-productive-people-dr-john-briffa-fit-to-succeed-podcast

Workplace wellness for highly productive people – Episode 49 with Dr John Briffa


There is no doubt that successfully managing the health of the human body has plenty of benefit for the workplace for all types of employment. However, the question is whether an employer or corporate organisation have the right to interfere with their employee’s lifestyle and health-related habits? Also what realistic actions can be taken to make a difference in workplace wellness, productivity and efficiency? Dr John Briffa, a leading voice within corporate health and wellbeing, joins us on today’s show to answer these important questions.

Guest biography

Dr John Briffa is a practising medical doctor, author and international speaker. He is a prize-winning graduate of University College London School of Medicine, and also holds a BSc degree in Biomedical Sciences. 

Dr Briffa is a former columnist for the Daily Mail and the Observer newspapers in the UK, and former contributing editor for Men’s Health magazine and is a previous recipient of the Health Journalist of the Year award in the UK.

Dr Briffa has authored nine books including A Great Day at the Office (Harper Collins 2014), a practical guide to optimising energy and performance for business professionals. He is the director of Dr Briffa Wellness, a specialist consultancy that provides speaking and training services to organisations and business professionals around the world. Clients include Deloitte, PwC, HSBC, Barclays, the Bank of America Merrill Lynch, Allen and Overy, Gowling WLG, the BBC, Tesco and Schroders.

Episode content: Workplace wellness

In this discussion, John shares some great perspectives, insights, and health tips that will benefit your working habits and lifestyle more broadly. John’s gift for communication and personable style make this a great, easy listening episode that is well worth your listening time! 

  • 1:48 What motivated Dr Briffa to work within the field of corporate wellness
  • 7:44 The responsibility of the employer and employee in personal wellbeing
  • 10:46 Workplace rights to interfere versus the personal right to choose
  • 17:54 The workplace as an option to reach individuals and affect health change
  • 22:43 The cause and a potential solution to mid-afternoon fatigue
  • 30:10 How poor sleep can impact productivity and performance
  • 37:37 Managing stress load within the work environment
  • 52:50 Quick-fire questions: sunlight exposure, breathing techniques, & music at work

Connect with Dr Briffa via social media

Twitter: @drbriffa

Linkedin: @dr john briffa

Dr Briffa’s books

Rate the show

If you enjoyed this episode focused on supporting workplace wellness, then please rate the show, give a short review, and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes or the video series on YouTube so you will receive each update immediately upon release.

For other great episodes and expert guests on the Fit to Succeed show, visit the full podcast library.


Poor sleep? Coaching your chronotype – Episode 40 with Nick Littlehales


Chronic sleep loss is becoming a problem of epidemic proportions in modern society. Could your genetic chronotype have something to do with your ability, or inability, to get the needed hours of rest and recovery? If you find you regularly experience poor sleep then perhaps this discussion with sleep coach and author, Nick Littlehales will open your eyes to potential solutions.

Guest biography

Nick Littlehales is a pioneer in the field of sleep coaching within UK sport, with more than 2 decades of experience helping to deliver innovative and practical solutions to real-life problems around sleep. Nick’s fascinating journey to become the world’s leading Elite Sport Sleep Coach and his revolutionary R90 Technique is encapsulated in a book called  SLEEP.

Image result for nick littlehales
Elite Sport Sleep Coach: Nick Littlehales


Episode content: Poor sleep

Following a fascinating review of Nick’s journey, somewhat ahead of the curve, into the field of sleep coaching, we discuss in detail the importance of chronotype on our daily routine and preferences. There is plenty to enjoy and learn in this down to earth and easy listening discussion about resolving poor sleep issues. Key subjects include:

  • 1.43: Nick’s early motivation to work within the field of sleep coaching for athletes
  • 8.43: Modern science has revealed a large amount of definitive data about sleep and health
  • 10.06: The background to the book SLEEP and the subsequent rise in popularity
  • 14.02: The importance of sleep within modern-day sporting performance
  • 18.20: Standard sleeping conditions in modern high-level athletic accommodation
  • 21.58: What is chronotype?
  • 29.18: Managing individual variation in chronotype within team sport environments
  • 40.18: In relation to the time of day does chronotype influence the level of athletic performance?

Sleep course

If this topic interested you, why not become a Sleep Recovery Specialist with Nordic Fitness Education through our online course. Visit Sport Sleep Coach to get access to a 20% discount code and save €50 on the list price. Alternatively, contact us directly!

Connect with Nick on social media

Facebook @sportsleepcoachuk

Instagram @_sportsleepcoach

Twitter @sportsleepcoach

Buy Nick’s book about Sleep

Click the book cover to find Nick’s book on Amazon, available in paperback, e-book, or audio.

Image result for nick littlehales

Rate the show

If you enjoy this episode, then please rate the show, give a short review, and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes or the video series on YouTube so you will receive each update immediately upon release.

For other great episodes and expert guests on the Fit to Succeed show, visit our full podcast library.


Coaching habit change in sport – Episode 36 with Adam Feit


Supporting athletes, or the general public, through habit change in sport, exercise, diet and daily food intake can be a tricky road to navigate at times. Adam Feit from Precision Nutrition offers guidance and direction on how to best coach others in the world of sports nutrition and behaviour change.

Guest biography

Adam Feit is a Level 2 Master Class Coach as well as the Performance Nutrition Coordinator at the global educator, Precision Nutrition. He has years of experience working with youth, collegiate, Olympic and professional athletic teams including the Calgary Flames, Brooklyn Nets, and the ALTIS track and field club.

Adam is certified by the National Strength & Conditioning Association (NSCA) as a Registered Strength and Conditioning Coach and a Certified Strength and Conditioning Specialist. He is also a Certified Strength and Conditioning Coach and a mentor from the Collegiate Strength and Conditioning Coaches Association.

He is the co-author of the Coaches Guide to Jump Training and Complete Guide to Training the Female Athlete. Adam is also a PhD Candidate in Sport and Exercise Psychology.


Adam Feit sports nutrition

Episode content: Coaching habit change

This interview and fascinating discussion covered a broad range of subjects around sports nutrition, supporting new behaviour, and habit change.

  • 1.35: Adam’s ranking of the importance of diet and nutrition in supporting an athlete’s overall goals
  • 4.47: Exercise alone may not be the most effective strategy to help athletes (or the general public) lose weight
  • 13.03: The importance of meal plans and macronutrients as the drivers for dietary change
  • 18.44: How to determine what are the ‘big rocks’ or priorities when supporting clients through nutritional or behavioural change
  • 24.56: When to stick rigidly to a preset plan versus when it is best to adapt and adjust a plan of action
  • 29.25: How to develop a flexible, periodised nutrition plan
  • 32.05: An explanation of habit stacking and how to use it

Connect with Adam and Precision Nutrition

Precision Nutrition Level 1 certification opens only twice per year. The next intake is coming up shortly in October 2019. Adam invites you to get signed up here.

 Facebook @insidePN


 Twitter @insidePN

Rate the show

If you enjoy this episode, then please rate the show, give a short review, and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes or the video series on YouTube so you will receive each update immediately upon release.

For other great episodes and expert guests on the Fit to Succeed show, visit our complete podcast library.


Sleep recovery for health, exercise and weight loss – Episode 33 with Ben Pratt


Recently the creator of our Sleep Recovery Specialist course, Ben Pratt, was interviewed on the Pro-Fit podcast (episode 7) by Matt Robinson, a member of the Pro-Fit Personal Training team. With the permission of Pro-Fit we are featuring the video recording of the full interview as episode 33 of the Fit to Succeed podcast. Enjoy.

Guest biography

Ben Pratt has worked within the health and fitness industry since 1995 across a wide range of different roles. In 2003 he refocused his career towards education and has been teaching and developing coursework for fitness professionals ever since. Ben’s formal education includes a BSc. in Sports Science and an MSc. in Holistic Nutrition. His research and course development work has included more specialist fields such as obesity and diabetes, nutrition for physical performance, postural assessment and corrective exercise, suspension training, and the importance of sleep for exercise performance and recovery, weight loss and muscle growth. Ben is also the author of Nutrition’s Playground and the Complete Guide to Suspended Fitness Training.

Ben Pratt – leading fitness educator

Episode content: Sleep recovery

During this episode, a wide range of topics was discussed, including:

  • the importance of sleep to health and wellbeing
  • how sleep habits have changed during the last 3 decades
  • why correctly assessing sleep habits and behaviours is important
  • the powerful connection between chronic sleep loss and weight gain
  • fundamental principles to train circadian rhythm and establish effective sleep
  • ideas and strategies to help develop good sleep habits in young children
  • how to correctly utilise naps to help improve performance following periods of sleep loss

If you enjoy this episode, then please rate the show and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes, Stitcher or Spotify, or the video series on YouTube so you will be notified of each new episode immediately upon release. To enjoy more of our engaging expert interviews, please visit our podcast library.

We invite you to learn more about the Sleep Recovery Specialist certificate and to register on the course using the discount code SRSDROP20 to get 20% off the course price.

About Pro-Fit Personal Training

Pro-Fit PT is the leading personal training company in the north-west of England, founded by Graham Webb and Steve Butters back in 2002. The Pro-Fit team is now over 140 personal trainers strong, spread across a wide range of gym and fitness clubs across the region. Pro-Fit pride themselves on delivering high-level customer service with motivational coaching to help each client optimise their fitness and nutrition in the achievement of their goals.

Click here to learn more about the successful Pro-Fit Personal Training business.

Pro-fit Personal Training logo

Goal achievement through brain-body connection, Episode 26 with Marcel Daane


Neuroscientist, leadership coach, and personal trainer, Marcel Daane, shares some great insights into goal achievement and how the brain and body can be more effectively integrated and be in harmony to reach your important objectives.

Guest biography

Marcel is the recipient of the 2016 Global Coaching Leadership Award and 2012 Global HR Excellence Award in Leadership as well as the author of HeadStrong Performance. He is the son of a celebrated political activist and former member of an elite naval intelligence unit. Marcel changed career in his thirties to become a personal trainer and then progressed with advanced degrees in Neuroscience of Leadership and Complementary Medicine.

With over 20 years of coaching experience across business, sports, health, and cognitive performance, Marcel’s integrated approach has transformed the lives of thousands of executives. His expertise has helped improve the performance of numerous multi-national organizations around the world, from a wide range of industries.

Episode content: Goal achievement

In this episode on goal achievement with Marcel Daane, we discuss:

  • what motivated Marcel to change career and become a personal trainer
  • the important connection between the brain and the body as a foundational concept for leadership and performance
  • what is resilience and why it is key to both physical and mental performance
  • why outside-the-box thinking is essential for modern fitness professionals

If you enjoy this episode, then please rate the show and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes or the video series here on YouTube so you will receive each update immediately upon release. To enjoy more engaging expert interviews, please visit our full podcast library.


Connect with Marcel on social media:

Facebook @HeadstrongPerformanceBook     Facebook @marceldaane

Instagram @marceldaane

Twitter @MarcelDaane

Bonus Video

Marcel also shared a short bonus video to capture a few key concepts about resilience, mental focus, and why outside-the-box thinking is so important to fitness professionals today.


Personal coaching supersedes personal training – Episode 25 with Bobby Cappuccio


Coaching is not just another word for training! Becoming a personal fitness coach requires a change in our approach to client support and behaviour change. Leading behaviour coach and personal trainer, Bobby Cappuccio, shares the important differences and will be sure to change your perspective.

Guest biography

Bobby began coaching shortly after a paradigm shift occurred in his life. He was in his early twenties and a certified personal trainer. Born with a severe facial deformity and diagnosed with Tourette syndrome at age nine, he suffered abominable abuse in and out of his home until he stumbled upon a marvel: exercise. He discovered that by redirecting his focus, he could affect positive change in not only his life but in the lives of the people he in turn trained. In helping others, he was in fact helping himself. In sharing his discoveries over the years, he became a world-renowned speaker, author and behaviour change coach.

As co-founder of PTA Global, former head of training and development at David Barton gym, former director of professional development at the National Academy of Sports Medicine (N.A.S.M.), Director of Coaching at the Institute of Motion (IOM) and content curator for PTontheNet, Bobby’s reach runs wide. Bobby has worked with Hilton Hotels, Virgin Active, Fitness First, 24hr Fitness, David Lloyd Leisure and multiple small businesses nationally and abroad. Bobby travels the world impacting lives, inspiring positive change and growth in individuals and companies alike. He has presented at business and fitness conferences across the globe including IDEA, Filex, CanFitPro, FitPro, IHRSA, Pure Fitness Asia, Perform Better, Equinox, Gold’s Gym International, Lifetime Family Fitness etc. helping to develop top-notch fitness professionals.

Fit to Succeed episode: Personal coaching

In this episode on personal coaching we cover:

  • Bobby’s back story that brought him into the fitness and personal training industry
  • the definition of coaching
  • how personal training is connected to coaching
  • the concept of cognitive dissonance and how this can impact fitness objectives
  • how confirmation bias can lead to less informed choices and limit the potential for change

If you enjoy this episode, then please rate the show and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes or the video series here on YouTube so you will receive each update immediately upon release. To enjoy more engaging expert interviews, please visit our full podcast library.


Connect with Bobby on social media

Facebook @TheRobertCappuccio

Instagram @bobbycappuccio

Twitter @bobbycappuccio

Bonus video

Here is a short 5-minute bonus video that we recorded with Bobby, that offers some extra ideas and concepts to help.


Motivation and confidence for fitness trainers – Episode 19 with Pete Cohen


Health and fitness professionals are human too! It may come as a surprise that many in the fitness industry still struggle with a lack of motivation and confidence and maybe even a lack of self-belief. Sometimes developing and maintaining a high level of fitness is a means to overcoming those personal limitations. However, there is another way…learn to motivate yourself, begin an action plan to gradually increase in confidence and self-belief for true success. World-leading expert and inspirator, Pete Cohen, joins us on the Fit to Succeed show and shares vital insights into how we can build our psychological muscles!

Guest biography

Pete Cohen is one of the world’s leading keynote speakers. Hundreds of thousands of people from all over the world have been motivated and inspired by Pete’s presentations. He has been dedicated to supporting organisations and the people within them to flourish for over 25 years.

Pete coaches business leaders, executives, corporate teams and sporting stars to achieve their best. He has worked with companies such as IBM, Boots, Pfizer, Robert Half International, BAA, Royal Bank of Scotland, Boehringer Ingelheim and Thomas Cook. He has professionally impacted on the lives of thousands of people worldwide. Pete focuses on the importance of having a strong belief in yourself.

He is the author of 17 published books, several of which have been best-sellers across the world, including Shut the Duck UpHabit BustingLife DIY and Sort Your Life Out. He has also presented his own show on TV called The Coach and was the resident Life Coach on GMTV for 12 years. Pete’s background is in psychology and sports science. He specialises in taking self-help and personal development to the masses in a way that is easy for people to understand and apply. Working in sports performance coaching, Pete has helped world class sporting stars reach their peak performance. Notable clients include Sally Gunnell, Ronnie O’Sullivan, Ellen MacArthur, Roger Black, the Kent Cricket Team and the Arsenal Football team.

Pete Cohen – the Inspirator

Episode Content: Motivation and confidence

In this episode with Pete Cohen we discuss some intriguing topics and draw out some fascinating insights, including:

  • what motivated Pete to become a fitness professional
  • what is ‘self help’ and why do we need it?
  • how to ensure we receive help from qualified coaches
  • actions for developing confidence and self-belief
  • how to shift from a negative relationship with exercise/diet to a more positive one


motivation confidence & self belief

Connect with Pete on social media

Facebook @Itspetecohen

Instagram @petecohen_

Twitter @petecohen_

If you enjoy this episode about motivation confidence & self-belief, then please rate the show and share it with your friends so they can benefit from this free expert information. Your comments and feedback are always welcome. Please subscribe to the podcast on iTunes or the video series on YouTube so you will receive each update immediately upon release. To enjoy more engaging interviews, visit our full podcast library.

Episode links

During episode 19 Pete mentioned a range of different books, experts and talks that you can find out more about by following the links below:

Mel Robbins TEDX talk: How to stop screwing yourself over

Episode 11 Fit to Succeed podcast with Pete’s past fitness colleague, Lincoln Bryden, a leading group exercise expert

Book recommendations:

Think and grow rich by Napoleon Hill

The Heroes Journey by Joseph Campbell

Pete Cohen’s Mi365 podcast

Bonus video

This short bonus interview was recorded in addition to the main interview. Pete shares some quick thoughts to help those who need some ideas in a hurry! Enjoy.


Stressed out? The root cause – Episode 9 with Pete Williams


Does life sometimes get too much? Being stressed out has a significant impact on our day to day lives and developing resilience is a necessary factor in our modern world. Functional medicine practitioner and stress expert, Pete Williams, unfolds some intriguing insights around managing stress in this episode of the Fit to Succeed show.

Guest biography

Pete Williams is a graduate from the University of Liverpool, with a BA in exercise physiology, 1992. He went on to obtain a Master of Medical Science from The University of Sheffield in 1995. He is a Fellow of the Royal Society of Medicine (1997) and a Certified Strength and Conditioning Specialist, NSCA 1999. Pete was the youngest recipient of the ‘Lifetime Achievement’ award from the UK Register for Exercise Professionals, 2003. He graduated from the Institute for Functional Medicine (2004) and was one of the first to be awarded the Institute for Functional Medicine Certified Practitioner status (2013). He is considered a clinical innovator by the Institute for Functional Medicine.

Working in central London, Pete has considerable experience in supporting clients as they seek to recover from the damage that stress can have on the body.

Pete Williams, Functional Medicine practitioner

Episode content: Stressed out? The root cause

In this fascinating episode of the Fit to Succeed show, with Pete Williams, we discuss the following:

  • the primary physiology behind the stress response
  • common intrinsic and extrinsic stressors in our modern environment
  • identifying the total burden upon a client
  • is there a tipping point where the burden exceeds the ability to recover?
  • how to identify the root cause of stress-related dysfunction
  • top strategies for supporting the management of stress and its effects

If you enjoy this expert interview episode, then please rate the show and share it with your friends so they can benefit from this free information. Your comments and feedback are always welcome. Please subscribe to the Fit to Succeed podcast on iTunesStitcherPlayer FM or the full version on YouTube so you will receive each update immediately upon release. To enjoy more engaging expert interviews, visit the full podcast library.


Connect with Pete on Social media:

Facebook @petefmed

Instagram @petefmed

Twitter @petefmed


Should you get your Vitamin D from sunlight or diet?


The question

Vitamin D is absolutely integral to human health! This vital ‘nutrient’ provides many benefits to the body. Even though we still refer to it as a vitamin or a nutrient, the vast majority (approximately 90%) of active vitamin D3 in the body is produced when our skin is exposed to sunlight. So that’s it then, we should get our vitamin D from sunlight, debate over! Not so fast! This topic is a little more nuanced than that. Sufficient, effective sun exposure on a regular basis can be tricky to achieve. It is certainly possible to consume vitamin D from the diet, but there are only a very limited number of food sources that contain sufficient amounts to meet daily requirements. As a result of these 2 key issues, it is now estimated that 40-75% of the world’s population is vitamin D deficient! (1) That´s right – you could be one of the 7 out of 10 people with low vitamin D, so read on to learn how to resolve this. 

Functions of vitamin D

Firstly why do we need vitamin D? Scientific studies have shown that vitamin D is needed for and supports a wide range of health-related functions: (2)

  • Necessary for bone strength by aiding the absorption of calcium, phosphorus and magnesium to lay down new bone tissue
  • Helps to regulate vascular health and may positively influence blood pressure
  • Stimulates insulin secretion from the pancreas and may reduce diabetes
  • Supports both infectious and inflammatory immune system response
  • Potent antioxidant properties with some research suggesting potential for anticarcinogenic properties and reduced cancer mortality
  • Supports oestrogen production, may help to regulate the menstrual cycle and reduce symptoms of PMT
  • Has beneficial effects on the brain and may reduce the risk of cognitive decline and dementia

Vitamin D from sunlight

If sunlight exposure is the primary method of receiving up to 90% of this incredibly important nutrient, then we really should understand more about the complex relationship between sunlight and human exposure.

Standing outside on a bright sunny day, feeling the warmth of the sun on your skin, is a prized experience in the colder climates both north and south of the tropical and sub-tropical regions of the world, especially after a long winter season. Whereas for those living in the relentless heat of the tropical zones, it is an ongoing, daily battle to keep cool and avoid sunburn with much less fluctuation across the seasons!

Exposure to the rays of the sun (UVB wavelength) is known to help generate vitamin D through the conversion of a naturally occurring precursor under the skin called 7-dehydrocholesterol (7-DHC). This is converted into pre-vitamin D3, which is then rearranged into the active form of vitamin D3.

The standard guidelines indicate that the body needs a minimum of 20-25 mcg or 800-1000 IU of vitamin D per day. Although, it must be noted that reaching this minimal nutrient status is a different matter to preventing all adverse effects from insufficent vitamin D. A group of scientists in the vitamin D research community are advocating a daily requirement 4 times higher at 4000 IU per day to ensure optimal health effects (1). However, reaching this level of vitamin D from sunlight alone on a hot summer’s day would likely lead to sunburn for lighter skinned people.

Sunlight stimulates the conversion to vitamin D3

How much vitamin D is actually produced when the skin is exposed to sunlight depends upon a range of factors, including:

  • Time of day
  • Season of the year
  • Geographical latitude
  • Altitude
  • Length of sunlight exposure
  • How much skin is directly exposed to the sun
  • The colour or pigmentation of the skin

Time and season

Both the time of day and the season of the year make a difference to our ability to get vitamin D from sunlight exposure. This is related to the angle of the sun’s UV rays passing through the earth’s atmosphere and also the proximity of our geographical location on the globe to the sun itself.

The changing path of the sun in the sky throughout a day

In the early morning and late evening, the suns rays shine upon us at a sharper angle, causing them to pass through a greater distance of the earth’s atmosphere. The atmosphere helps filter the suns rays reducing Ultraviolet intensity (UVI). Lower UVI at these times of day means less conversion of 7-DHC to active vitamin D3 as well as less chance of sunburn. Conversely, the higher the sun is in the sky, the more direct the sun’s rays are in relation to our location. This means less distance to pass through the atmosphere, higher UVI and more rapid conversion of 7-DHC to vitamin D3, but also a much faster sunburn time too.

The earth spins around a central axis point, however, that axis is not vertical, it sits at a titled angle of 23.5 degrees in relation to its orbit around the sun. It is this tilted axis that gives earth its annual seasons. The northern and southern hemispheres gradually change in their position to the sun, being closer in the summertime and further away in the wintertime. This change in distance between the earth’s surface and the sun alters the length of day and the peak UVI. The UVI at midday in the summer will be much higher than UVI during winter midday. As already stated a reduced UVI will affect the rate of conversion to vitamin D3. It has been well documented that vitamin D deficiency rates are higher in winter months. (3) In the temperate and frigid zones of the earth, above and below 42 degrees latitude, there will be periods during winter (approximately November to February) when it will be very difficult to convert any 7-DHC to vitamin D3 at all, due to limited UVB radiation that can reach the earth’s surface.

Sunlight exposure and UVI changes across seasons

Latitude and altitude

In addition to the time of day and season of the year, the latitude on the earth’s surface will also play a part in the angle of the sun’s rays through the atmosphere. The further north or south an individual is positioned on the planet, the more atmosphere sunlight will need to pass through and the lower the UVI will be relative to equatorial zones at the same time of year.


The ozone layer is the portion of the earth’s atmosphere that largely protects us from the strong UVB rays that cause sunburn and stimulate vitamin D conversion. Some UVB does still makes it through the ozone into the atmosphere below (troposphere). The higher the altitude above sea level, the greater the UVI will be due to the thinner atmosphere present at that location to help filter UVB rays. UVB radiation increases approximately 7% every 1000m in elevation above sea level (4). As a general rule, higher altitudes result in cooler temperatures, but conversely higher altitudes also mean a higher risk of sunburn due to increased UVB exposure. The higher UVI at altitude also speeds up the conversion process so that more vitamin D is formed in less sunlight exposure time.

Higher altitude leads to greater UVB exposure

Length of time and amount of skin exposed

Body surface areas – rule of 9’s

Regardless of the time of year or the geographical position on planet earth, the length of exposure time to the sun’s UVB rays is directly correlated to a greater opportunity to covert 7-DHC to vitamin D3. But this time of exposure for vitamin D production must be balanced carefully against the risk of burning the skin and causing damage as a result. The skin coverage of the clothing we choose to wear and the colour of an individual’s skin will also play an important part in determining the time exposed to UVB necessary to reach our daily vitamin D from sunlight requirement. The image below will provide some guidance regarding the percentage of skin exposed to sunlight based on which body parts are clothed or not.

The general guidance offered is to expose 18% of the body (face, arms and ahands) to the summer sun around mid-morning or mid-afternoon for 6-10 minutes in order to stimulate the conversion of up to 1000 IU of vitamin D. In the winter times this exposure may need to be increased up to 45 minutes. Well, at least these general guidelines apply to sub-tropical and temperate zones and lighter-skinned people. These rules will need to be adapted for hotter tropical zones and darker-skinned people.

Skin pigmentation

Fitzpatrick skin type classification

The natural pigment in human skin, called melanin, is present in varying amounts and gives rise to the different shades and colours of skin across the human population. Melanin absorbs and prevents UVB from passing through the skin layers. This helps to reduce the risk of sunburn and skin damage, but it also means that less vitamin D from sunlight is produced under the skin of those with higher melanin levels. There are 6 types according to the Fitzpatrick skin type categories. Type 1 is the lightest skin through to type 6 the darkest pigmentation. It is estimated that darker-skinned people may require 3-6 times longer sun exposure to produce the same relative vitamin D as lighter-skinned individuals.

Dietary vitamin D

So where does dietary vitamin D fit in after this extensive focus on sunlight exposure and all its compounding variables? Firstly, it should be quite obvious that getting enough vitamin D from the sun during the warmer summer months should be relatively easy to achieve with daily, fairly short outdoor sun exposure, even for those with darker skin. The summer is the least likely time to experience vitamin D deficiency.

It is the winter season when dietary sources of vitamin D become a very important contributor to maintaining our levels of this beneficial nutrient. The increased risk of vitamin D winter deficiency can be offset by carefully planning some simple inclusions in your diet. This is especially important for those living in the temperate and frigid zones, above and below 42 degrees latitude north or south.

Tropical, Temperate, and Frigid Zones on Earth

Vitamin D is a fat-soluble nutrient, meaning it is only available within naturally occurring foods that have sufficient amounts of fat contained within them. The richest sources being primarily from fish and shellfish. Some food sources may be fortified with vitamin D (synthetic form added), but keep an eye out for the addition of the less effective, cheaper vitamin D2 form, instead of the more beneficial active vitamin D3 form.

Top 10 naturally occurring food sources of Vitamin D

Cod liver oil has been used as a nutritional supplement for hundreds of years, especially in the colder, temperate countries in the northern hemisphere. Whilst science now understands the benefits of omega 3 fats and vitamin D, perhaps traditional wisdom had worked out there was something good in this particular oil that helped them weather the physically challenging winter months a little better. Cod liver oil is a food ‘supplement’ and whilst it is the richest source per 100g, it will usually only be consumed 1-2 tablespoons (15-30ml) per day. This small amount will still deliver 1500-3000 IU so is a useful additional source of vitamin D.

A few commonly consumed foods, not sourced from the oceans, that provide smaller amounts of vitamin D include egg yolks (2.6 mcg/100g), butter (1.4 mcg/100g), and beef liver (1.1 mcg/100g). These fatty, naturally occurring foods will help contribute small, but beneficial amounts to our personal vitamin D reservoir during the short days and longer nights of winter.

If the above foods are difficult to source or just not to your taste preferences, then the use of supplementation may be warranted during winter months. In 2011 researchers at Bastyr University in California ran a study comparing vitamin D3 supplementation in 3 different forms; oil drops, capsules or chewable tablets. They showed that when taking high doses of 10,000 IU (250 mcg) of vitamin D3 daily for 12 weeks, all 3 forms proved to be both safe and effective, and significantly increased levels in the blood (6). The recommended daily intake varies depending upon the organisation you choose to rely upon from 1000 IU (25 mcg) to 4000 IU (100 mcg) per day.

Conclusion: Vitamin D from sunlight or diet

So as it turns out, it is not a matter of sunlight versus diet in the vitamin D stakes. Both have their place throughout the seasons of the year. When the sun does makes an appearance during the spring, summer, and autumn seasons we should seek to enjoy some regular exposure on our skin to allow for natural vitamin D formation. Not only it is good for our biology, it is also good for the mind and emotions to get outside and bathe in sunlight. If we get sufficient sunlight during the warmer months, supplementation will not be necessary at that time of year.

  • Between 6-20 minutes of summer sunlight for skin types 1 – 3, between 20-45 minutes for skin types 4 – 6 of summer sunlight – the variation will depend on the time of day, season, temperature, latitude, and altitude.
  • 18% (face, hands and arms) to 36% (face, hands, arms & legs) of the skin’s surface should be exposed to sunlight.
  • Sunlight for vitamin D should not be hindered by sunscreen, which potentially blocks the UVB rays we need to facilitate vitamin D conversion.
  • If your shadow is longer than you are tall, then the UVI is lower and slightly longer time in the sun will be required, if your shadow is shorter than you are tall then UVI is higher and shorter times in the sun are advised.
  • Sun exposure to get sufficient vitamin D will not require any reddening or burning of the skin.
  • If exposure to the sun will go beyond the individualised time limit for optimal vitamin D, then it would be appropriate to cover the body with clothing or to utilise a thorough covering of sunscreen to prevent sunburn.

During the winter months when sunlight is rare, we must then become more dependent upon natural dietary sources of vitamin D from cod liver oil, fish and seafood. If this is not practical and you want to be certain, then also including a good quality vitamin D3 supplement to ensure our physiological needs are met may be an important strategy during the colder months of the year.








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