New research lends some insight as to why chronic stress and sleep deprivation are linked with obesity. Cortisol, a stress hormone, is normally released in regular bursts throughout the day while we are awake. This occurs as long as a normal circadian rhythm is maintained. If cortisol is released for long periods of time, such as if one stays awake longer than 12 hours in a day, this lack of sleep leads to more fat cells. The body replaces only 10 percent of the fat cells in the body each year, but cortisol causes the pre-fat cells in the body to become fat cells when the hormone is released for pro- longed periods. It is becoming clear why it is important to maintain a proper amount of sleep.

(Source: American Society for Cell Biology Meeting, December 12-16, 2015)