Objective: Sleep loss represents an increasingly common condition in industrialized societies. So, we studied the effect of total and partial sleep deprivation on both metabolic and endocrine functions in adult and old aged male rats. Methods: we induced sleep deprivation by random alarming light and sound on 40 adult and 40 old aged male rats. Then we measured, body weight, BMI, rectal temperature, T3,T4,TSH, PRL, corticosterone, insulin, and FBG before and after TSD and PSD [for one night, one week, and two weeks]. Results: A decrease in body weight. BMI, R. temperature, insulin and FBG, thyroid hormones with normal or even low TSH was noticed. An increase of corticosterone level was found especially after TSD in old aged rats. Conclusion: A state of hypercatabolism, hypothyroid state, and altered resiliency of HPA axis was noticed after sleep deprivation (mainly after TSD) with minimal effect of age difference.