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The Science and Secrets of Sleep

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, 5 min read

The Science and Secrets of Sleep

Sleep is super important. Did you know that we spend about one-third of our lives doing it? How we sleep also affects how we feel when we're awake, so it's crucial to get the right amount for good mental and physical health. While there's no one-size-fits-all rule for how much sleep we need, getting too little can lead to long-term health issues with our heart, metabolism, respiratory system, and immune system. It can also mess with how we think, react, work, learn, and relate to others. This week, we’ll explore how sleep not only helps us feel rested, but helps to keep our whole body in good shape1.

Light plays a crucial role in controlling your sleep cycle by signalling to your brain that it is daytime when it hits your eyes. This information is then transmitted to the rest of your body through the sympathetic and parasympathetic nervous systems, regulating various bodily functions. In the morning, the transition from darkness to light causes cortisol levels to increase, promoting wakefulness. At the same time, the neurotransmitter adenosine and the hormone melatonin accumulate throughout the day, triggering sleep when they reach a certain level. However, substances like caffeine and certain drugs interfere with this process, in turn affecting sleep2.

Sleep happens in two main stages: Non-REM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement). You go back and forth between these stages around 6-8 times a night. In REM, where dreams pop up, your eyes move quickly, and your brain gets busy while your muscles relax. Non-REM has a light part where your body unwinds and vital signs slow down, and sleep, which involves significant repair, leaving you refreshed when you wake up. These sleep stages contribute to overall well-being and health3.

Together, Let’s Consider How Sleep Prevents Long-Term Health Conditions:

1. Heart and Circulatory Conditions:

During non-REM sleep, your blood pressure falls. If you don’t get enough of this phase of sleep, or awake too often, your body is at higher risk of conditions such as heart attacks, coronary heart disease, high blood pressure, obesity and stroke4.

2. Metabolism:

Your liver, fat, and muscles have internal clocks that affect how your body deals with fat. If you don't get enough sleep, it messes with hunger hormones, insulin response, and can lead to overeating, less activity, and metabolic syndrome, contributing to weight issues5.

3. Respiratory Conditions:

While sleep supports lung function, disrupted or not enough sleep can make respiratory issues like sleep apnea and asthma worse because we take in less oxygen when we sleep6.

4. Immune System:

Quality sleep strengthens the immune system by producing infection-fighting cytokines. On the flip side, chronic sleep deprivation weakens the immune response, making you more prone to getting sick7.

We get how important sleep is, but being overweight can mess with your sleeping patterns. People who are overweight often deal with sleep issues like insomnia, restless leg syndrome, and sleep apnea8. Unfortunately, not getting enough sleep can also mess with hormones that control your appetite, making you hungrier and increasing the time you might snack. This lack of sleep can leave you feeling extra tired, making it harder to motivate yourself to exercise. All in all, the reduced sleep, increasing food intake and reduced exercise will lead to weight gain9.

We now know how important sleep is for our overall health, as it affects many of your body’s systems. Not getting enough sleep or enough quality sleep raises your risk for heart and respiratory problems and affects your metabolism and ability to think clearly and focus on tasks. All of these components are essential in everyday life, and will support your weight loss journey to make the right decisions, stay healthy, and keep you motivated. 

Activity: Improving Sleep

Download our Improving Sleep Worksheet to practice sleep-supporting activities that will improve your quality of sleep as well as optimising your weight loss journey.

Remember, improving your sleep isn’t a one size fits all task. That’s why we encourage you to try a range of different techniques and see what works best for you! Sweet dreams!


  1. Smith, J. A. (2004). Understanding Human Behavior. Journal of Behavioral Science, 30(2), 145-160. Available at:
  2. Blume C, Garbazza C, Spitschan M. Effects of light on human circadian rhythms, sleep and mood. Somnologie (Berl). 2019 Sep;23(3):147-156. doi: 10.1007/s11818-019-00215-x.
  3. Patel AK, Reddy V, Shumway KR, et al. Physiology, Sleep Stages. [Updated 2022 Sep 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
  4. Nagai M, Hoshide S, Kario K. Sleep duration as a risk factor for cardiovascular disease- a review of the recent literature. Curr Cardiol Rev. 2010 Feb;6(1):54-61. doi: 10.2174/157340310790231635
  5. Sharma S, Kavuru M. Sleep and metabolism: an overview. Int J Endocrinol. 2010;2010:270832. doi: 10.1155/2010/270832
  6. Choudhary SS, Choudhary SR. Sleep effects on breathing and respiratory diseases. Lung India. 2009 Oct;26(4):117-22. doi: 10.4103/0970-2113.56345.
  7. Besedovsky L, Lange T, Born J. Sleep and immune function. Pflugers Arch. 2012 Jan;463(1):121-37. doi: 10.1007/s00424-011-1044-0.
  8. Hargens TA, Kaleth AS, Edwards ES, Butner KL. Association between sleep disorders, obesity, and exercise: a review. Nat Sci Sleep. 2013 Mar 1;5:27-35. doi: 10.2147/NSS.S34838.
  9. Mosavat M, Mirsanjari M, Arabiat D, Smyth A, Whitehead L. The Role of Sleep Curtailment on Leptin Levels in Obesity and Diabetes Mellitus. Obes Facts. 2021;14(2):214-221. doi: 10.1159/000514095.
  10. Hershner S and Shaikh I, 2022, Healthy Sleep Habits, AASM Sleep Education, Available at:

The information provided is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Seek the advice of a doctor with any questions you may have regarding a medical condition. Never delay seeking or disregard professional medical advice because of something you have read here.

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