This paper reports the results of measurements of metabolism and body temperatures taken during 14 nights of comfortably warm sleep in six male Eskimos from the village of Wainwright on the arctic coast of Alaska. The mean age of these subjects was 20. 8 (± 1. 26) years, mean height 169. 1 (± 5. 08) cm, mean weight 66. 6 (± 2. 0) kg and mean value for percent body fat 9. 1 (± 1. 08) %. These data show the effects of the sleep cycle on metabolism and body temperature. The sleeping metabolic rate declined from 50 {± 7. 35) kcal/m /hr at 2230 hours to 39 (± 5. 22) kcal/m²/hr at 0600 hours. Concomitantly, rectal temperature, which was negatively correlated with time (r = -. 965393), fell from 37. 0 (± . 386)°C at 2230 hours to 35. 4 (± . 386)°C by 0600 hours. Calculated mean body temperature was directly related to the level of metabolic activity. These coastal Eskimos had essentially normal values for early morning basal metabolic rates in contrast to Anaktuvuk Pass Eskimos from the interior of Alaska who are hypermetabolic.