Losing weight is challenging, and keeping weight off can be just as difficult. Although the medical community is still untangling the complicated relationship between sleep and body weight, several potential links have emerged that highlight the potential weight loss benefits of getting a good night’s rest and the negative health impacts of sleep deprivation.
The Connection Between Sleep and Weight
Over the past several decades, the amount of time that Americans spend sleeping has steadily decreased1, as has the self-reported quality of that sleep. For much of the same time period, the average body mass index (BMI) of Americans increased, reflecting a trend toward higher body weights and elevated rates of obesity.
In response to these trends, many researchers began to hypothesize about potential connections between weight and sleep. Numerous studies have suggested that restricted sleep and poor sleep quality may lead to metabolic disorders, weight gain, and an increased risk of obesity and other chronic health conditions.
While there is continuing debate within the medical community about the exact nature of this relationship, the existing research points to a positive correlation between good sleep and healthy body weight.
There remains much to be discovered about the intricate details of how sleep and weight are connected. Several hypotheses offer paths for additional research with the hope that increasing our understanding of the relationship between weight and sleep will lead to reduced obesity and better weight-loss methods.
Can Lack of Sleep Increase Appetite?
One common hypothesis about the connection between weight and sleep involves how sleep affects appetite. While we often think of appetite as simply a matter of stomach grumbling, it’s actually controlled by neurotransmitters, which are chemical messengers that allow neurons (nerve cells) to communicate with one another.
The neurotransmitters ghrelin and leptin are thought to be central to appetite. Ghrelin promotes hunger, and leptin contributes to feeling full. The body naturally increases and decreases the levels of these neurotransmitters throughout the day, signaling the need to consume calories.
A lack of sleep may affect the body’s regulation of these neurotransmitters. In one study, men who got 4 hours of sleep had increased ghrelin and decreased leptin compared to those who got 10 hours of sleep. This dysregulation of ghrelin and leptin may lead to increased appetite and diminished feelings of fullness in people who are sleep deprived.
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.
Other hypotheses regarding the connection between sleep and increased appetite involve the body’s endocannabinoid system and orexin, a neurotransmitter targeted by some sleep aids.
Many researchers believe that the connection between sleep and dysregulation of neurotransmitters is complicated and additional studies are needed to further understand the neurobiological relationship.
Does Sleep Increase Metabolism?
Metabolism is a chemical process in which the body converts what we eat and drink into energy needed to survive. All of our collective activities, from breathing to exercising and everything in between, are part of metabolism. While activities like exercise can temporarily increase metabolism, sleep cannot. Metabolism actually slows about 15% during sleep, reaching its lowest level in the morning.
In fact, many studies have shown that sleep deprivation (whether due to self-induction, insomnia, untreated sleep apnea, or other sleep disorders) commonly leads to metabolic dysregulation. Poor sleep is associated with increased oxidative stress, glucose (blood sugar) intolerance (a precursor to diabetes), and insulin resistance. Extra time spent awake may increase the opportunities to eat, and sleeping less may disrupt circadian rhythms, leading to weight gain.