Total sleep deprivation decreases immobility in the forced-swim test

Sleep deprivation can exert antidepressant effects in humans in less than 24 h, making it the fastest acting antidepressant treatment. However, it is rarely used clinically because the effect disappears once the subject goes back to sleep. An understanding of the neurobiological mechanisms underlying the antidepressant effect of sleep deprivation should help to develop new rapidly acting antidepressant strategies. In the present report, an animal model of depression (the forced-swim test) was used to determine whether the effects of total sleep deprivation parallel those obtained with antidepressant drugs. Using the disk-over-water method, rats deprived of sleep for 24 h exhibited increased swimming behavior when compared to cage control rats, mimicking the effects of serotonergic antidepressants. After 48 h, sleep-deprived rats exhibited increased swimming when compared to both cage control and stimulus control rats, demonstrating that the effect is due to sleep deprivation per se, and not to extraneous factors inherent in the sleep deprivation protocol (such as stress and movement). We believe that this paradigm can be used to study the neurobiological mechanisms of rapid antidepressant effects induced by sleep deprivation.