Why adequate sleep may be as important as what we eat

The Importance of Sleep

The Importance of Sleep

Author: Kirstie Lamb, Researcher and Trainer in Public Health/31 January 2018

Sleep is often overlooked as a lifestyle component that can affect our health. However, research suggests that obtaining sufficient good quality sleep may be as important as our diet for maintaining good health; both physical and psychological. This week’s blog discusses how much sleep to aim for, associated health benefits of obtaining sufficient sleep and top tips to try and improve the quantity and quality of your sleep.

How much sleep do we need?

The NHS recommends that we get around 8 hours of good quality sleep every night. Although in reality, some of us will need more whilst others require less (www.nhs.uk/oneyou/sleep)! Despite this recommendation, a survey undertaken by The Sleep Council in 2017 found that ¾ (74%) of the UK population sleep less than 7 hours per night and 17% sleep less than 5 hours per night (The Sleep Council 2017).

It has been suggested that the quality of the sleep we get may be more important than the quantity (Pilcher 1997, Cappuccio et al. 2010). There are 4 stages in each sleep cycle and it is proposed that we need to go through this cycle 5-6 times per night in order to feel fully refreshed in the morning. Each cycle lasts around 1 ½ hours and the 4 stages are as follows:

Sleep and your health

Inadequate sleep (both quantity and quality) can be detrimental to your health. There are several health effects associated with poor sleep and these are discussed below:

Increased hunger and appetite:

Ghrelin is a hunger hormone. When levels of this hormone are increased, appetite is stimulated. Ghrelin levels have been shown to increase after sleep restriction (Broussard et al. 2015). In contrast, leptin is a fullness (satiety) hormone; i.e. when levels of this are increased, we are stimulated to feel full and have a reduced appetite. Reduced sleep duration has been associated with reduced leptin levels, suggesting that inadequate sleep may lead to reduced appetite suppression (Taheri et al. 2004).

Weight gain:

Reduction in the quantity/quality of sleep has been associated with an increase in body mass index (BMI) and adiposity. Snacking episodes have been shown to increase as a result of a lack of sleep (Broussard et al. 2015); this may be a consequence of increased ghrelin and reduced leptin, causing these individuals to feel more hungry.

Furthermore, studies have demonstrated that individuals are more likely to crave and consume high-energy, sugary foods in greater quantities when they are lacking adequate sleep. A combination of increased hunger hormones, suppressed satiety hormones, increased snacking and poorer food choices may explain the association between weight and inadequate sleep. Increased levels of stress hormones, such as cortisol, and insulin (a nutrient storage hormone) observed following inadequate sleep may also contribute to weight gain.

Poorer mental health:

Individuals reporting more frequent insufficiency of sleep have been found to be more likely to suffer from depression and anxiety. Suggesting that sleep is important for improving mental wellbeing (Strine and Chapman 2005). However, it cannot be determined whether poorer mental health is a cause or an effect of inadequate sleep. As most evidence is from observational studies (read about limitations of observational studies here).


A lack of or poor quality sleep is also linked to stress, as it can contribute to disrupted stress hormone levels, such as cortisol (Hirotsu et al. 2015). Read our previous blog here to learn more about this.

Top tips to get a good night’s sleep

Ensure the room isn’t too warm (or too cold!). Too cold and it may be harder for you to fall asleep. But too warm and it may lead to a restless night’s sleep. It is suggested that 16-18ᵒC is the ideal room temperature to sleep in, however this will vary between individuals (https://sleepcouncil.org.uk/perfect-sleep-environment/). Use a hot water bottle or extra blankets if it’s cold and a thinner duvet when it’s warmer e.g. in the summer.

Ensure that the room is dark. We release melatonin when it is dark, which is a chemical that helps us to relax. Try blackout blinds or an eye mask if you find you are woken up early by the sun rising.

Don’t use electronic devices before going to bed and ensure that these are turned off if kept in your bedroom. These devices often omit a blue light, which suppresses the release of melatonin whilst decreasing ‘sleepiness’ (Chang et al. 2015). Bleeps and noises (and even vibrations!) can also disrupt your sleep. You may not be woken up by these, but the quality of your sleep can be affected

Ensure your mattress is suited to you and your weight/build, offering adequate support and comfort. Mattresses should be replaced every 7-8 years to maintain the support you need for a good night’s sleep!

Avoid caffeinated drinks or alcohol before bed. Alcohol may help you drift off to sleep quicker, but it can disrupt the quality of your sleep!



Broussard, J. L., J. M. Kilkus, F. Delebecque, V. Abraham, A. Day, H. R. Whitmore and E. Tasali (2015). “Elevated ghrelin predicts food intake during experimental sleep restriction.” Obesity.

Cappuccio, F. P., L. D’Elia, P. Strazzullo and M. A. Miller (2010). “Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis.” Diabetes Care 33(2): 414-420.

Chang, A. M., D. Aeschbach, J. F. Duffy and C. A. Czeisler (2015). “Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness.” Proc Natl Acad Sci U S A 112(4): 1232-1237.

The Sleep Council (2017). The Great British Bedtime Report 2017.

Hirotsu, C., S. Tufik and M. L. Andersen (2015). “Interactions between sleep, stress, and metabolism: From physiological to pathological conditions.” Sleep Science 8(3): 143-152.

Pilcher, J., Ginter, D., & Sadowsky, B (1997). “Sleep Quality versus Sleep Quantity Relationships between sleep and measures of health, well-being and sleepiness in college students.” Journal of Psychosomatic Research 42(6): 583-596.

Strine, T. W. and D. P. Chapman (2005). “Associations of frequent sleep insufficiency with health-related quality of life and health behaviors.” Sleep Med 6(1): 23-27.

Taheri, S., L. Lin, D. Austin, T. Young and E. Mignot (2004). “Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index.” PLoS Med 1(3): e62.

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