Sleep loss in male rats contributes more to weight gain during sleep disruption than stress assessed by corticosterone

Sleep disruption (SD) promotes stress which may mediate the effect of SD induced by noise on bodyweight gain and food intake. We determined if the change in bodyweight during SD caused by noise was driven by stress (assessed by corticosterone) and whether the effects of noise on SD, stress and bodyweight were specific to the method of SD or a consequence of SD per se. We isolated stress from SD due to noise by exposing rats to noise during the dark_phase to test whether dark_phase noise stimulated weight gain, stress and food intake. Male Sprague-Dawley rats slept undisturbed, were exposed to noise during both circadian phases (light_phase vs dark_phase) and light_phase gentle handling. Bodyweight, food intake, physical activity, vigilance states, and plasma corticosterone were determined. Dark_phase noise did not affect vigilance states. Unlike light_phase noise, dark_phase noise and light_phase gentle handling did not stimulate weight gain or food intake. Only gentle handling significantly increased corticosterone levels. Noise during the light_phase increasesed weight gain and food intake by causing SD and these effects were not driven by stress as assessed by corticosterone. These results may have significant implications for developing translational models of insomnia-induced obesity in humans.