Lack of sleep is causally connected to many physical problems. We know that from numerous reliable studies.
Obstructive Sleep Apnea (OSA) is a major cause of sleep loss and one of the common symptoms of (OSA) is being overweight. Sleeping less than six hours — or more than nine hours — a night appears to increase the likelihood of weight gain. So then, how does OSA effect weight gain?
There are three hormones that factor in the equation of lack of sleep contributing to weight gain.
1. Ghrelin: the Hunger Hormone
Lack of sleep increases ghrelin, and decreases leptin, both effects producing increased hunger and obesity. Ghrelin is produced in the gastrointestinal tract and functions as a neurotransmitter. When the circadian rhythm is interrupted by exposure to light at night, gherlin is released.
2. Leptin: the Anti-hunger Hormone.
Leptin is the satiety hormone that has opposite effects from ghrelin. The receptor for leptin is found on the same cells in the brain as the receptor for ghrelin.
Melatonin maintains the body’s circadian rhythm by regulating the other hormones. The circadian rhythm is an internal 24-hour “clock” that plays a critical role in when we fall asleep and when we wake up. When it is dark, your body produces more melatonin. When it is light, the production of melatonin drops. Being exposed to bright lights in the evening, or too little light during the day, can disrupt the body’s normal melatonin cycles. For example, jet lag, shift work, and poor vision can disrupt melatonin cycles.
Melatonin supplements can be helpful for those who are sleep disadvantaged but adherence to directions is recommended.
An inverse relationship between the hours of sleep and blood concentrations of ghrelin exists: as the hours of sleep increase, ghrelin levels trend lower and obesity is less likely. Short sleep duration is associated with high levels of ghrelin and obesity.
When the stomach is empty, ghrelin is secreted. When we eat something the stomach is stretched and ghrelin secretion stops. Ghrelin acts to increase hunger and to increase gastric acid secretion and gastrointestinal motility to prepare the body for food intake.
What else does Ghrelin do to effect weight gain?
Beyond regulating hunger, ghrelin also plays a significant role in other systemic functions. Ghrelin influences body composition, it stimulates the release of growth hormone and regulates the distribution and rate of use of energy.
This is just another convincing reason to get adequate healthy sleep…. at the right time. Light is the circadian rhythm disrupter. Avoid light disturbances during sleep: have no lights in the bed room, pull the shades down to block any outside light, wear an eye mask.
Psychology Department, University of Cyprus, Nicosia 1678, Cyprus.
- Department of Cell Biology, Physiology and Immunology, University of Cordoba, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), and CIBER Fisiopatología de la Obesidad y Nutrición, 14004 Córdoba, Spain.