Ten rats were subjected to total sleep deprivation (TSD) by the disk apparatus. All TSD rats died or were sacrificed when death seemed imminent within 11-32 days. No anatomical cause of death was identified. All TSD rats showed a debilitated appearance, lesions on their tails and paws, and weight loss in spite of increased food intake. Their yoked control (TSC) rats remained healthy. Since dehydration was ruled out and several measures indicated accelerated use rather than failure to absorb

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... ients, the food-weight changes in TSD rats were attributed to increased energy expenditure (EE). The measurement of EE, based upon caloric value of food, weight, and wastes, indicated that all TSD rats increased EE, with mean levels reaching more than twice baseline values. Key Words: Total sleep deprivation-Debilitation-Skin lesions-Food and weight-Energy expenditure. In a previous study with the disk apparatus (1), total sleep deprivation (TSD) produced death, diverse pathology, and weight loss in spite of increased food intake. The present TSD study was undertaken to replicate those results and to obtain additional data, which might help explain them. METHOD Procedures and nomenclature were described in Part II in this series (2). Of 12 TSD runs started, two were discarded because the TSD rats were sacrificed after 4 and 7 days when death seemed imminent, apparently due to histologically verified pneumococcal infections. Because such infections sometimes occur in normal rats after surgery and no other sleep-deprived rats showed similar infections, the contribution of TSD to the pathology was not clear. Of the remaining 10 runs, nine were with intracardiac cannulas. RESULTS AND DISCUSSION Sleep data In the 10 TSD rats, mean baseline sleep quotas, as a percentage of total time, were: total sleep (TS) 53.4 ± 4.6 SD; paradoxical sleep (PS) 5.9 ± 0.4; non-rapid eye move-