THE FIRST NIGHT EFFECT: AN EEG STUDY OF SLEEP

Abstract: Department of Psychology College of Arts and Sciences and Department of Psychiatry College of Medicine the University of Florida Gainsville Florida and the J. Hillis Miller Health Center Department of Psychiatry Gainsville Florida SUMMARY AND CONCLUSIONS The data from 43 young adults whose EEG sleep characteristics were measured during four consecutive nights of sleep patterns between the first night and the three succeeding nights are presented. More specifically the first night was characterized by (1) significantly more Stage 0 and Stage "1" and less Stage I-REM (2) a delayed onset of Stages IV and I-REM and (3) more stage changes. Except in the case of stage changes these differences were small and insignificant between the second and fourth nights of laboratory sleep. Adaptation to laboratory sleep appears to be quite rapid in terms of these particular variables. These data validate the common procedure of eliminating the first night of laboratory sleep from descriptions of baseline data. In terms of the increased number of awakenings the lowered I-REM time and the greater number of stage changes it would appear that an the first night the subject is generally in a more aroused state and indeed tests his environment more frequently than an succeeding nights. ___MH

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