EFFECT OF NIGHT MEDICAL GUARD ON FOLLOWIN G DAY VIGILANCE - INFLUENCEOF AN HYPNOTIC MEDICATION ON RECOVERY NIGHT AND ON THE VIGILANCE DURING THE FOLLOWING DAY

The consequences of sleep deprivation on vigilance and mood were evalu ated in six healthy medical students the day after being on night duty and the following day, after recovering from a full night's sleep. Di urnal vigilance was studied using the Multiple Sleep Latency Test (MSL T) and mood was assessed on an anxiety self-evaluation scale. The stud y was conducted by means of a double-blind randomized trial to measure the effects of benzodiazepine (lormetazepam, 2 mg) compared to a plac ebo administered before the night recovery/full night's sleep. Sleep d eprivation induced a significant decrease in vigilance the day followi ng the night duty. Sleep latencies were shortened during the morning f ollowing the night of recovery/full night's sleep. The Values obtained after administering the lormetazepam did not differ significantly fro m those obtained after administering the placebo. There were no consid erable differences in the anxiety evaluation scores before and after t he night of recovery/full night's sleep between the two sequences of t he trial. This study suggests that a significant lack of sleep (a 36-h our sleep deficit) modifies diurnal vigilance over two nyctohemeral pe riods. Administration of benzodiazepine with a short half-life after o ccasional sleep deprivation does not change the reorganization of the sleep-waking cycle.