Is Sleep Deprivation a Contributor to Obesity?

Photo of Jean-Philippe Chaput

Author: Jean-Philippe Chaput, Ph.D.
Assistant Professor of Pediatrics, University of Ottawa, Canada

The possibility that sleep – the most sedentary activity of all – contributes to the obesity epidemic is gaining recognition in the scientific community. In a world that values productivity, time is a precious commodity. It is therefore not unusual for people to cut down into their sleep time to finish everything they believe has to be done in a day, or to wind down before heading to bed. In fact, it is becoming more common for people to view less sleep as beneficial and associated with being “hardworking”. Unfortunately, many people ignore the negative impact of this type of behavior on their health. Fortunately, recent research into the effects of sleep is helping people become aware of the benefits of good sleep hygiene for overall health. 

The term “lack of sleep” generally refers to an insufficient amount of sleep for optimal functioning. While the ideal amount of sleep per night varies from one person to another, sleep recommendations issued by the National Sleep Foundation (see below) suggest that adults sleeping less than 7 hours per night and school-age children sleeping less than 9 hours per night are at higher risk of gaining weight and having poor health outcomes than those with adequate sleeping habits. Also, we need to keep in mind that healthy sleep includes dimensions other than sleep quantity such as sleep quality, timing, architecture, consistency, and continuity. 

Sleep recommendations issued by the National Sleep Foundation.

Age

Recommendation (hours/day)         

Newborns (0-3 months)    14-17 hours
Infants (4-11 months) 12-15 hours
Toddlers (1-2 years) 11-14 hours
Preschoolers (3-5 years)   10-13 hours
School-aged children (6-13 years)                      9-11 hours
Adolescents (14-17 years)   8-10 hours
Adults (18-64 years)   7-9 hours
Older adults (≥65 years) 7-8 hours

 

In order to induce weight gain, reduced sleep must either increase food intake and/or reduce energy expenditure. The mechanisms by which lack of sleep can cause weight gain are illustrated below. On a hormonal level, lack of sleep may disrupt a number of hormones that affect our drive to eat. Less time spent sleeping also means more time and opportunities for eating. Lack of sleep has been shown to increase snacking, the number of meals eaten per day, and the preference for energy-dense foods. Increased food intake associated with a lack of sleep can also be seen as a normal physiological adaptation to provide energy needed to sustain additional wakefulness. On the other side of the energy balance equation, sleep loss generally leads to a general feeling of fatigue, which can make us feel less inclined to want to do physical activity.   

Most plausible mechanisms by which a lack of sleep may lead to weight gain.

Chart showing most plausible mechanisms by which a lack of sleep may lead to weight gain

Click here to view a larger version of the chart

 

In summary, sleep deprivation is common in modern societies, and there is now robust evidence supporting the role of reduced sleep as contributing to the current obesity epidemic. Increased food intake seems to be the main explanation as to why a lack of sleep can lead to weight gain. Future research should aim to examine the clinical benefits of increasing sleep duration on eating behaviors and body weight control. Additionally, we need to better understand the importance of adequate sleep to improve the treatment of obesity. Given that behavioral sleep restriction appears to be linked to our modern way of living, short sleepers may find it difficult to maintain a healthy lifestyle in the current environment that promotes overconsumption of food and sedentary behaviors. Sleep is not a “waste of time”, and public health efforts should aim to better promote a good night’s sleep for overall health.