Nutritional and metabolic adaptations to prolonged sleep deprivation in the rat

Abstract

To understand how and why sleep deprivation is physically harmful, we explored the possible causal relationship between its two main effects, 1) negative energy balance and 2) a composite of symptoms that resemble protein malnutrition, both of which occur despite increased food consumption. We provided balanced diets augmented with either protein or calories (by increased fat content) to freely moving rats. Interactions between sleep deprivation symptoms and energy and protein supplies were assessed from measurements of body weight regulation, consumption of macronutrients, clinical chemistry and hematology profiles, and physical appearance. The results indicate that sleep deprivation causes malnutrition, which is secondary to increased energy expenditure. Even though food consumption remained normal in sleep-deprived rats fed a diet of high protein-to-calorie ratio, body weight loss was more than 16% of baseline, development of skin lesions was hastened, and longevity was shortened by 40% compared with sleep-deprived rats fed the calorie-augmented diet. Food consumption of the calorie-fed rats was lower during baseline than that of the protein-fed group but during sleep deprivation increased to amounts 250% of normal without net body weight gain. Despite a fat-laden diet the calorie-fed hyperphagic group did not have abnormal levels of plasma cholesterol, triglycerides, or glucose, indicating accelerated turnover of nutrients. As would be consistent with calorie malnutrition, pronounced clinical chemistry or hematological abnormalities were not found in any group. Beneficial effects of the calorie-augmented diet are attributed to 1) caloric density of fat, 2) induction of hyperphagia, and 3) efficiency of utilization of fat. We conclude that diet composition interacts strongly with sleep deprivation, affecting the time course and development of pathologies, whereas it exerted negligible influence on body weight regulation under normal conditions.

Effects of prolonged sleep deprivation on local rates of cerebral energy metabolism in freely moving rats

“…The duration of each experiment was a 4 week period that included at least 7 d for recovery from surgery, 7 d of baseline conditions, and 11-12 d of experimental sleep conditions. The sleep deprivation procedure has been described in detail previously (Rechtschaffen et al, 1983: Everson and Wehr. 1993.…”

“…This computer-assisted scoring was validated by visual comparison with 24 hr analog recordings. Continuous measurement of body temperature in 30 set epochs was obtained from the telemetric transmitters, the signals ofwhich were picked up by AM band receivers, passed through level detectors to discriminate signal from noise, digitized, and timed by a microprocessor (Everson and Wehr, 1993). Core body temperature measurements were aligned with the corresponding sleep stage for each epoch.…”

“…This dietary modification has previously been shown to attenuate the weight loss and malnutrition-like effects in sleep-deprived rats (Everson and Wehr, 1993). Body weight and food and water intake were recorded daily throughout the baseline and experimental periods.…”

Recurrent restriction of sleep and inadequate recuperation induce both adaptive changes and pathological outcomes

“…However, rats that obtain nearly half-normal sleep amounts during the same time period do not develop severe pathology and do not die (20,53,55,62). They typically do, however, show abnormalities in metabolic, hormonal, and immune-related parameters that are less severe than those observed under total sleep deprivation conditions (2,18,20,21,24,28). Whether these changes are clinically important and whether an individual can adapt to sub-par sleep amounts are issues that bear on the relevance of sleep to physical health and its role in development and recuperation from disease.…”

“…83). Already well established is the fact that acutely sustained total sleep deprivation in laboratory rats results in a progressive negative energy balance (2,20,28), suppression of major anabolic hormones (21,24), and immune-related abnormalities (18,19,26,27) that turn lethal after an average of 16 to 21 days (20,53,55,62). However, rats that obtain nearly half-normal sleep amounts during the same time period do not develop severe pathology and do not die (20,53,55,62).…”