Get enough sleep and establish a regular sleep schedule for better body composition and hormone regulation. Research shows that in men, sleep duration and chronotype—the natural tendency to have more energy in the morning or evening—significantly affect testosterone and related hormone levels. This in turn affects insulin metabolism and body composition. Similar results have been found in women, although the hormonal response is slightly different.
A recent study found that men who slept based on their natural chronotype had higher testosterone than those who didn’t time their sleep based on natural tendency. Subjects who were forced to go against their chronotype (such as an “evening” subject who had to get up early) had lower testosterone. The obvious take away is to embrace your chronotype and go to bed based on your tendency. Try to avoid changing bedtime drastically on the weekend.
Another study shows that the effect of short or unnatural sleep time influences the entire hormonal cascade, which is one reason sleep is so important for body composition. Researchers tested the effect of sleep restriction for five nights in young, healthy men. They were allowed to sleep only four hours each night.
Results showed that just a few days of inadequate sleep decreased testosterone a small amount, while significantly increasing the average cortisol level at all time points throughout the day. Cortisol was on average 15.5 percent higher, and a related stress hormone, ACTH, was 3.2 percent higher. Most significant, subjects experienced an impaired blood sugar response after eating breakfast when sleep deprived, and insulin was nearly 30 percent higher.
There were some strange findings too—the hormone leptin, which blunts hunger, was higher, while triglycerides were lower, which could be positive for health in the long term. However, because sleep deprivation appears to cause complete disregulation of the hypothalamic pituitary axis that regulates hormones, energy levels, and hunger, the longer term effect to these biomarkers is more likely to be detrimental for health.
It’s also possible that the favorable leptin and the triglyceride readings were a result of the fact that food was carefully regulated during the study and participants were only allowed to eat at meals and only what was served. Other sleep deprivation studies in which subjects have been allowed to eat whatever they want have found that people favor high-fat, high-sugar foods when exhausted and tend to eat about 300 calories more than usual.
To get better sleep and support body composition, identify your chronotype and submit to it. Go to be at the same time each night and try to stay on that schedule for the weekend whenever possible. For more sleep tips, read the Top Ten Tips on Increasing Quantity and Quality of Sleep
Reynolds, A., Dorrian, J. et al. Impact of Five Nights of Sleep Restriction on Glucose Metabolism, Leptin, and Testosterone in Young Adult Men. PLOS One. 2012. 7(7), e41218.
Randler, C., Ebenhoh, N., et al. Chronotype but not Sleep Length is Related to Salivary Testosterone in young Adult Men. Psychoneuroendocrinology. 2012. 37. 1740-1744.