Does a lack of sleep encourage weight gain?

Sleep has become a hot topic in the world of health, and research highlights the broader issues of sleep deprivation extending way beyond simply feeling tired. One particular area of interest is the impact of chronic sleep deprivation on body weight and studies suggest that sleep deprivation is independently associated with a higher risk of obesity.

A study published in the American Journal of Epidemiology found people who sleep less than 5 hours a night eat more during the day (1).  A further study found people who slept 5 hours or less a night had the highest BMI and greatest weight gain when compared to those who slept for 7 hours (2).

But does this mean that if you don’t sleep well, you will get fat?

What is the role of sleep?

Sleep is defined as “A condition of body and mind which typically recurs for several hours every night, in which the nervous system is inactive, the eyes closed, the postural muscles relaxed, and consciousness practically suspended.”

A lot is going on once you fall asleep. The body needs a surprising amount of energy to fuel these functions, including memory processing, muscle and joint recovery, and growth. Poor sleep impacts mood, concentration, and alertness, and the effects of long-term sleep deprivation have been linked to several severe health conditions, including heart disease, diabetes, and stroke (3).

How well are we sleeping?

Optimally, we should all be aiming to get around 8 hours of sleep a night. However, according to research carried out by the Royal Society for Public Health, it appears most of us only manage to get less than seven.

Over a week, this deficit equates to a whole night’s sleep, and research by The Sleep Council has shown that 33 percent of people only manage 5–6 hours, while 7 percent get less than 5 hours.

Researchers at Loughborough University found that those who habitually slept for less than six hours each night tended to have a higher BMI than those who managed to get the recommended eight nightly hours.

Does sleep deprivation affect our appetite hormones?

Research has suggested that a lack of sleep may impact the hormones leptin and ghrelin, which control appetite. Leptin sends signals to the brain to help inhibit hunger, while ghrelin is released by the stomach to stimulate appetite. The research suggests that a lack of sleep may reduce leptin and increases ghrelin which may be a factor for weight gain in non-sleepers.

In one study, men who got four hours or less of sleep had increased ghrelin and decreased leptin compared to those who got 10 hours. This dysregulation of such hormones could lead to increased appetite and a reduced feeling of fullness in sleep-deprived people (4).

This hormonal effect may explain the correlation between obesity and sleep deprivation highlighted by specific studies, but more research is needed.

In addition, several studies have also indicated that sleep deprivation affects food preferences. Sleep-deprived individuals tend to choose foods that are high in calories and carbohydrates (5).

Insulin and sleep

Insulin, the hormone that regulates blood sugar, may also be affected by sleep. This hormone also promotes the storage of fat, and as such, it has been suggested that higher levels may impact weight gain. One published study found that sleep deprivation may increase the release of insulin and another hormone called cortisol which has also been associated with fat storage in the body (6).

How does being overweight affect our ability to sleep?

Being overweight can affect our ability to sleep in a couple of ways. Sleep apnoea is a condition that affects breathing during the night which can disrupt sleep. If this is an issue, make sure you sleep on your side to help open up the airways.

Indigestion is another problem that interrupts sleep and is more common in overweight people. Heartburn is a common symptom of indigestion as stomach acid rises into the oesophagus and throat.

Does this all mean that poor sleep makes you overweight?

Definitely not as the research is far from definitive. There may also be a much simpler connection….

Sleep deprivation causes fatigue and tiredness, impacting our motivation to eat well and keep active. Chronic sleep deprivation could also affect mental health contributing to low mood, depression, and anxiety. Such mental health conditions may lead to erratic eating behaviours such as skipping meals, comfort eating, or binging on unhealthy foods, contributing to weight gain.

The possible link between sleep and body weight is just one of many areas of research on this topic. Maintaining a healthy body involves diet and exercise but sleep should be a consideration.

References 

1. Xiao, Q., Arem, H., Moore, S. C., Hollenbeck, A. R., & Matthews, C. E. (2013). A large prospective investigation of sleep duration, weight change, and obesity in the NIH-AARP Diet and Health Study cohort. American journal of epidemiology, 178(11), 1600–1610.
2. Patel, S. R., Malhotra, A., White, D. P., Gottlieb, D. J., & Hu, F. B. (2006). Association between reduced sleep and weight gain in women. American journal of epidemiology, 164(10), 947–954. 
3. Cappuccio, F. P., Cooper, D., D’Elia, L., Strazzullo, P., & Miller, M. A. (2011). Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies. European heart journal, 32(12), 1484–1492.
4. Motivala, S. J., Tomiyama, A. J., Ziegler, M., Khandrika, S., & Irwin, M. R. (2009). Nocturnal levels of ghrelin and leptin and sleep in chronic insomnia. Psychoneuroendocrinology, 34(4), 540–545. 
5. Zuraikat, F. M., Makarem, N., Liao, M., St-Onge, M. P., & Aggarwal, B. (2020). Measures of Poor Sleep Quality Are Associated With Higher Energy Intake and Poor Diet Quality in a Diverse Sample of Women From the Go Red for Women Strategically Focused Research Network. Journal of the American Heart Association, 9(4), e014587.
6. Hackett, R. A., Dal, Z., & Steptoe, A. (2020). The relationship between sleep problems and cortisol in people with type 2 diabetes. Psychoneuroendocrinology, 117, 104688.