Sleep and weight is the association between the amount of sleep an individual obtains and the weight of that individual.
Numerous studies have demonstrated an association between sleep disturbances and weight gain, and more specifically, that sleep deprivation is related to overweight. Furthermore, body weight also influences the quality of sleep and the occurrence of sleep disorders like obstructive sleep apnea. Oversleeping may also contribute to weight gain.
Additionally, there is a decrease in sleep duration and quality among most populations due to modern lifestyles which include an increased time spent looking at artificial lights from screens. The availability of night-time use of electronic devices and communication devices are associated with shorter sleep duration and increased body weight in children.
Relationship between stress, sleep and weight
The biological reaction to a stressor is the activation of the HPA-axis. In a stressful environment the body will release multiple hormones including cortisol. Over a long duration high cortisol concentrations can have negative effects on the immune system, attention and memory and can increase the risk of psychological disorders, such as depression. Also, too much stress can have an impact on sleep and is a risk factor of insomnia.
Stress can have an effect on sleep patterns, food intake and consequently weight gain. Stress has been found to be associated with increased emotional reward of palatable foods, which in turn can also lead to obesity. There seems to be only a one-sided relationship between cortisol levels and sleep deprivation. High cortisol levels due to high stress can lead to decreased sleep duration. However, 24-hour sleep deprivation does not seem to lead to changes in cortisol levels in healthy adults.
However, it is believed that chronic sleep deprivation has a negative effect on the neuroendocrine system and seems to change the ways in which people deal with challenges. The first changes appear to be on emotional perception, but might also change the fundamental properties of the neuroendocrine stress axis in the long run.
Lack of sleep related to weight gain
Lack of sleep has been strongly associated with weight gain in a variety of studies across all ages, though research suggests children and adolescents are particularly vulnerable. However, the exact mechanisms in which sleep deprivation leads to weight gain are diverse. Sleep deprivation is believed to have an influence on body weight in several different aspects: Sleep deprivation influences the brain's response to high-calorie food by making it more attractive, which leads to high-energy food choices, affects the production of the hormones ghreline and Leptin.
Not only sleep reduction, also disruption of the circadian clock can have a negative impact on sleep architecture and metabolism, as shown in mouse models. In adolescence late bedtimes are related to a higher risk of getting obese and great bedtime shifts between weekdays and weekend were associated with greater severity of overweight and longer screen time use. In general, sleeping less than 7 hours per night increases the risk to be obese.
Another plausible explanation is that fatigue because of limited sleep reduces physical activity and thus energy expenditure, which predisposes weight gain. Others show a non-reciprocal relationship where fatness predicts less physical activity and also sleep duration predict fatness, but an association was not found in a model which includes all three factors.