Interrelationships between nocturnal sleep, daytime alertness, and sleepiness: Two types of alertness proposed

The authors studied daytime sleepiness and alertness (based on the Multiple Sleep Latency Test [MSLT] and Maintenance of Wakefulness Test [MWT]) and n octurnal sleep in 22 patients with depression/anxiety and in 47 nondepresse d patients with sleep apnea. The patients underwent two overnight sleep stu dies followed by underwent tests. In depressed patients, MWT scores correla ted negatively with total sleep time and stage 3. MSLT scores correlated ne gatively with total sleep time and with sleep efficiency. Apneic patients s howed a negative correlation between MWT results and amount of stage 1 slee p. MSLT results correlated positively with sleep onset latency on the prece ding overnight sleep study. Thus, in depressed patients, there is a paradox that with more disturbed sleep there is greater daytime alertness. In cont rast, the more disturbed the sleep is in sleep apnea patients, the move dif ficult if is to maintain daytime alertness.