Abstract Mkid 77

This study investigated the relationship between EEG indexes and perception of sleep depth (DEPTH) during Multiple Sleep Latency Tests (MSLT). Participants were five males (X=41.6 years) and six females (X=36.8 years) with clinical complaints of excessive daytime sleepiness. Each subject had five nap opportunities. Subjects completed the Stanford Sleepiness Scale (SSS) before each nap and completed a "0-5" point scale to indicate DEPTH of sleep (DEPTH "0" indicated awake and DEPTH "5" indicated deep sleep) after each nap. Only naps in which EEG sleep occurred were used for data analysis. Recordings were scored for standard sleep parameters and SS density. Total sleep time (TST) was positively correlated with DEPTH. Analysis of variance (ANOVA) showed that TST was significantly less for DEPTH "0" compared to DEPTH "1-4". SS density was positively correlated with TST but not with DEPTH. ANOVA showed SS density was significantly lower for DEPTH "0" and DEPTH "4" compared with DEPTH "1-3". SSS scores were unrelated to TST and DEPTH scores. These results indicated that TST was associated only with the subjective experience of being awake versus being asleep. SS density was related to the perception of intermediate DEPTH levels but not to the deepest level (DEPTH "4"). Decreased SS density at DEPTH "4" indicated either that SS is not sufficient for accurate sleep perception or that all sleep states are not homogenous in terms of subjective experience