Brain-mind states: I. Longitudinal field study of sleep/wake factors influencing mentation report length

Study objectives: To collect and analyze reports of mental activity across sleep/wake states. Design: Mentation reports were collected in a longitudinal design by combin ing our Nightcap sleep monitor with daytime experience sampling techniques. Reports were collected over 14 days and nights from active and quiet wake. after instrumental awakenings at sleep onset, and after both spontaneous a nd instrumental awakenings from REM and NREM sleep, Setting: All reports were collected in the normal home, work and school env ironments of the subjects. Participants: Subjects included 8 male and 8 female undergraduate students (19-26 years of age). Interventions: N/A Measurements and Results: A total of 1,748 reports, averaging 109 per subje ct, were collected from active wake across the day (n=894), from quiet wake in the pre-sleep onset period (n=58), from sleep onset (n=280), and from l ater REM (n=269) and nonREM (n=247) awakenings. Median report lengths varie d more than 2-fold, in the order REM > active wake > quiet wake > NREM appr oximate to sleep onset. The extended protocol allowed many novel comparison s between conditions. In addition, while spontaneous REM reports were longe r than those from forced awakenings, the difference was explained by the ti me within the REM period at which the awakenings occurred. Finally, intersu bject differences in REM report lengths were correlated with similar differ ences in waking report lengths. Conclusions: The use of the Nightcap sleep monitoring system along with wak ing experience sampling permits a more complete sampling and analysis of me ntal activity across the sleep/wake cycle than has been previously possible .