Paradoxical Sleep Deprivation and Sleep Recovery: Effects on the Hypothalamic–Pituitary–Adrenal Axis Activity, Energy Balance and Body Composition of Rats

Abstract

Numerous studies indicate that sleep deprivation alters energy expenditure. However, this conclusion is drawn from indirect measurements. In the present study, we investigated alterations of energy expenditure, body composition, blood glucose levels, plasma insulin, adrenocorticotropic hormone (ACTH) and corticosterone levels immediately after 4 days of sleep deprivation or after 4 days of sleep recovery. Rats were sleep deprived or maintained in a control environment (groups sleep-deprived/deprivation and control/deprivation). One half of these animals were sacrificed at the end of the deprivation period and the other half was transported to metabolic cages, where they were allowed to sleep freely (groups sleep-deprived/recovery and control/recovery). At the end of the sleep recovery period, these rats were sacrificed. After sleep deprivation, sleep-deprived rats exhibited loss of body weight, augmented energy expenditure and reduced metabolic efficiency compared to control rats. These alterations were normalised during the sleep recovery period. The body composition of sleep-deprived rats was altered insofar as there was a loss of fat content and gain of protein content in the carcass compared to control rats. However, these alterations were not reversed by sleep recovery. Finally, plasma levels of insulin were reduced during the sleep deprivation period in both control and sleep deprived groups compared to the recovery period. After the deprivation period, plasma ACTH and corticosterone levels were increased in sleep-deprived rats compared to control rats, and although ACTH levels were similar between the groups after the sleep recovery period, corticosterone levels remained elevated in sleep-deprived rats after this period. By means of direct measurements of metabolism, our results showed that sleep deprivation produces increased energy expenditure and loss of fat content. Most of the alterations were reversed by sleep recovery, except for corticosterone levels and body composition.

Increased food intake and changes in metabolic hormones in response to chronic sleep restriction alternated with short periods of sleep allowance

“…Both epidemiological and clinical data suggest that disturbed sleep may contribute to the development of various diseases, e.g., obesity and type 2 diabetes (4,6,7,12,36,37). Restricted sleep also leads to alterations in food intake and its regulatory hormones, particularly an increased appetite and preference for fat, together with increased levels of ghrelin and decreased levels of leptin (38, 39).There are several rodent models for sleep deprivation; for example, the disk-over-water method (8, 28), the inverted flowerpot (or platform) paradigm (13,24), and the slowly rotating drum paradigm (1,26,30). In general, the changes in blood hormone levels and food intake in these models are similar to the findings in humans.…”

“…Sleep deprivation decreased plasma insulin (13) and leptin levels (8), and increased food intake was observed in some (8,13,16,17,28,29) but not all studies (1). However, the most consistent finding among these studies is that sleep-deprived rats lose weight (1,8,13,16,17,28,29), which is in contrast to the human finding where a lack of sleep generally is associated with weight gain (6, 14).The reason for this difference between rats and humans is unknown. There is some indirect evidence that the differences in weight gain vs. weight loss might be related to the nature of the sleep restriction protocol.…”

Contributions of neuronal prion protein on sleep recovery and stress response following sleep deprivation

“…Previous studies had shown that sleep disturbances are frequently associated with stress exposure [1,3,18,24,28,32] and that SD is an effective stressor. Intracerebroventricular injection of CRF into rats induces arousal [46] and consequently reduces NREM sleep concomitant with a significant decrease in spectral power in lower frequencies (1-6 Hz) and increases in high frequencies (32-64 Hz) [8].…”

Sleep Disturbances and Glucose Homeostasis

“…33 When this method is used to deprive rats of REM sleep for four days, it leads to a decrease in plasma insulin levels, which is secondary to a significant reduction in body weight. 34 Another commonly used method in animal sleep restriction research is the disk over water method, extensively described by Rechtschaffen and colleagues. 35,36 In short, the experimental animal is housed on a horizontal disk above water.…”