Many of us struggle with getting a good night's sleep and for some COVID-19 has made this worse, ultimately having a huge effect on our daily lives, routines and consequently our sleep-wake cycle. Our sleep-wake cycle is one of the most well-known circadian rhythms and is essentially a daily pattern that determines the time we go to sleep and the time we wake up. Whilst sleeping habits are not often the first thing that springs to mind when looking to manage our weight, continuous research has revealed associations between these two factors. Although multiple studies have indicated that insufficient sleep is not a direct cause of weight gain, findings suggest a clear link between lack of sleep and an increased total energy (aka calorie) intake (TEE) and overall weight gain, when considering other mediating factors (Rachel R. Markwald et al., 2013).
Modern life has made it increasingly difficult to switch off at night thanks to technology, 24-hour gyms, bars and so on. Nevertheless, this doesn't mean that improving our sleep hygiene is impossible, and not only would it benefit overall health, it may also aid those who are struggling with weight loss or weight maintenance.
So how much sleep should we all be aiming for? The National Sleep Foundation has given the following recommendations:
|Age||Recommended Sleep Duration|
|New-borns (0-3 months)||14-17 Hours|
|Infants (4-11 months)||12-15 Hours|
|Toddlers (1-2 years)||11-14 Hours|
|Pre-schoolers (3-5 years)||10-13 Hours|
|School-aged Children (6-13 years)||9-11 Hours|
|Teenagers (14-17 years)||8-10 Hours|
|Young adults and adults (18-64)||7-9 Hours|
|Older Adults (65+)||7-8 Hours|
Research has shown the dramatic effects of compromising our sleep requirements on our total calorie intake, but also the types of foods we reach for, portion sizes and increased food cravings (Yang, C., Schnepp, J. and Tucker, R., 2019). It has been observed that decreasing sleep duration from 9 hours to 5 hours each night for 5 days increases average calorie intake by around 111 k/cal per day. In those getting less sleep (5 hours) there were also increased (42%) intake of post-dinner snacking, predominately on carbohydrate rich foods (Markwald, R., et al., 2013).
A small study, of 24 women aged 18-55, found that a 33% reduction in sleep was again linked to increased hunger, larger portion sizes and increased food cravings. Portion sizes of carbohydrate rich foods such as chips and rice and overall intake of fats were significantly higher (p<0.05) after having a shorter sleep duration (Yang, C., Schnepp, J. and Tucker, R., 2019). The physiological factors to explain this trend is due to parts of the brain, including the amygdala, frontal cortex and insula cortex, increasing appetite signalling and cravings for high-calorie dense foods despite not necessarily being physically hungry (Greer, S., Goldstein, A. and Walker, M., 2013). In addition, it is thought that another cause of overeating is to compensate on the energy lost from sleep deprivation in order to support the body’s homeostatic function and to therefore boost our energy levels and relieve tiredness (Greer, S., et al 2013).
Partial sleep deprivation has also been associated with a change in the gut microbiota and studies have suggested that these significant changes in the microbial population have been associated with insulin sensitivity, obesity and a disturbed metabolism. However, due to the complexity of the gut microbiota, further research is needed (Parkar, S., et al, 2019).
The two main sleep hormones that influence our sleep-wake cycle: Cortisol (aka the 'stress' hormone) and Melatonin. There are many environmental cues that affect our circadian rhythm including temperature, exercise, and the most influential, light (Suni, E. and Dimitriu, A., 2020). Darkness causes the pineal gland in the brain to produce the hormone melatonin (in addition to the help of the PER1 gene aka 'clock gene') to regulate sleeping patterns. High melatonin and low cortisol levels are required to sleep whilst high cortisol and low levels of melatonin are needed to wake us up.
So, the main question I am sure you have by now is how can I better my sleep hygiene? As with every habit, it is very important to make small, realistic changes and to ensure they are done one at a time – patience is a virtue, especially when it comes to changing your circadian rhythm. Print the list below and colour in all of the habits you are already practising. Next, focus on one habit at a time to work on. Once you have achieved it and feel as though it is comfortably set in your routine, colour it in and pick the next one. Continue this until all of the boxes are coloured in and you will be on your way to a good night’s sleep.
This blog post was written by Olivia Lecocq, a Registered Associate Nutritionist and employee of the NHS. Olivia runs her own weight management clinic and works with children with metabolic disorders. Olivia is also involved in nutrition related studies including an international study with the NHS. In addition, she has recently started solo on a new venture as a private Nutritionist. Find her on Facebook @OliviaEllen or on Instagram @oliviaellen_nutrition.
Greer, S., Goldstein, A. and Walker, M., 2013. The impact of sleep deprivation on food desire in the human brain. Nature Communications, 4(1).
Kunka, J., 2020. Melatonin And Cortisol - Thriven Functional Medicine Clinic. [online] Thriven Functional Medicine Clinic. Available at: <https://thrivenfunctionalmedicine.com/melatonin-and-cortisol/> [Accessed 27 August 2020].
Markwald, R., Melanson, E., Smith, M., Higgins, J., Perreault, L., Eckel, R. and Wright, K., 2013. Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain. Proceedings of the National Academy of Sciences, 110(14), pp.5695-5700.
Max Hirshkow et al. (2015). National Sleep Foundation's updated sleep duration recommendations: final report. Sleep Health: The Journal of the National Sleep Foundation. 1 (4), 233-243.
Parkar, S., Kalsbeek, A. and Cheeseman, J., 2019. Potential Role for the Gut Microbiota in Modulating Host Circadian Rhythms and Metabolic Health. Microorganisms, 7(2), p.41.
Rachel R. Markwald et al. (2013). Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain. Proc Natl Acad Sci U S A. 110 (14), 5695–5700.
Roberts, A., 2020. Fig. 1. Circadian Variation Of Melatonin And Cortisol (Adapted From.... [online] ResearchGate. Available at: <https://www.researchgate.net/figure/Circadian-variation-of-melatonin-and-cortisol-adapted-from-Sato-et-al-2014-Cortisol_fig2_291354022> [Accessed 26 August 2020].
Sleep Foundation. (2015). National Sleep Foundation Recommends New Sleep Times. Available: https://www.sleepfoundation.org/press-release/national-sleep-foundation-recommends-new-sleep-times. Last accessed 26/08/2020.
Suni, E. and Dimitriu, A., 2020. What Is Circadian Rhythm? - Sleep Foundation. [online] Sleep Foundation. Available at: <https://www.sleepfoundation.org/articles/what-circadian-rhythm> [Accessed 27 August 2020].
Suni, E. and Vyas, N., 2020. What Is Sleep Hygiene? - Sleep Foundation. [online] Sleep Foundation. Available at: <https://www.sleepfoundation.org/articles/sleep-hygiene> [Accessed 27 August 2020].Yang, C., Schnepp, J. and Tucker, R., 2019. Increased Hunger, Food Cravings, Food Reward, and Portion Size Selection after Sleep Curtailment in Women Without Obesity. Nutrients, 11(3), p.663.
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