Daytime sleepiness, performance, mood, nocturnal sleep: the effect of benzodiazepine and caffeine on their relationship.

The present study was part of a larger 3-day, 2-night double-blind parallel group design in which 80 young adult men were divided into eight treatment groups to examine the effects of benzodiazepines and caffeine on nocturnal sleep and daytime sleepiness, performance, and mood. The present study was done to examine further the relationship among daytime sleepiness, performance, mood, and nocturnal sleep and to determine if and how these relationships were affected by the nighttime use of benzodiazepine and the ingestion of caffeine in the morning. Subjects received 15 or 30 mg of flurazepam, 0.25 or 0.50 mg of triazolam, or placebo at bedtime and 250 mg of caffeine or placebo in the morning for two treatment days. Two objective (Multiple Sleep Latency Test and lapses) and two subjective (Stanford Sleepiness Scale and Visual Analog Scale) measures of sleepiness, five performance tests, and two mood measures (Profile of Mood Scale and Visual Analog Scale) were administered repeatedly on both days. Electroencephalogram sleep was recorded on both nights. Objective sleep measures of daytime sleepiness were not significantly related to either performance or mood, but subjects with greater daytime sleepiness had significantly longer and more efficient nocturnal sleep. Neither benzodiazepine or caffeine influenced these relationships. In contrast, higher estimates of subjective sleepiness were significantly associated with poorer mood and tended to be related to poorer performance. Caffeine significantly reduced these relationships. Nocturnal sleep measures were not related to subjective estimates of daytime sleepiness.