Regular sleep and behavioral rhythms improve body functions
We don’t feel right when we change our sleep or wake schedule, whether due to shift work, jet lag, or illness. Humans have daily behavioral cycles of sleeping and waking, and of fasting and eating, and endogenous cycles, such as temperature.
A recent study suggests that maintaining a regular behavioral cycle including sleeping hours, and adhering to other appropriate daily circadian cycles benefit in the proper functioning of one’s body, as shown by better blood sugar, insulin, leptin, and blood pressure levels.
Researchers of the study examined the metabolic, autonomic, and endocrine effects of disrupting the alignment between these cycles in adult subjects.
The participants underwent a multi- day protocol in an environment free of time cues. Two 24-hour baseline periods with eight-hour sleep opportunities at subjects’ regular time were followed by seven 28-hour cycles, with sleep and wake periods scheduled in 1:2 ratio. The subjects received isocaloric meals every four hours in wake periods. The participants were prohibited from performing exercise of any kind.
In subjects with misaligned or disrupted sleep and behavioral cycles compared with aligned ones, significant differences included leptin (17% lower), glucose (6% higher), insulin (22% higher), mean arterial blood pressure (3% higher), and sleep efficiency (22% lower).
Leptin is a natural hormone which plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is responsible for energy balance and suppresses the appetite center when one has had too much to eat already. Sleep-deprived individuals have been shown by other studies to have low leptin levels which make them eat more leading to obesity.
The observed increases in glucose possibly resulted from exaggerated postprandial glucose responses, despite the insulin increases. With maximal disruption of sleep and other behavioral circadian cycles, leptin suppression was maximal and cortisol levels were reversed; that is, lower at the beginning and higher at the end of a wake episode.