Attenuation of the first night effect: a secondary analysis

Abstract

This study undertook a secondary analysis of baseline sleep data from Nights 1 and 2 of a six-night sleep study originally designed to study the effects of a short-acting benzodiazepine on the arousals, body movements and quality of sleep in 12 healthy elderly postmenopausal women. The secondary analysis utilized a one-group pre-experimental design to analyze if modifications in the laboratory setting made a difference on the phenomenon of the first night effect (FNE). The subjects (range 64 - 82 years) were evaluated for changes in sleep continuity, architecture, and quality suggestive of FNE by comparing polysomnogram data from the two baseline nights in the sleep laboratory. All subjects were exposed to a sleep laboratory environment modified to resemble an apartment that incorporated subjects' familiar routines and items in an attempt to eliminate the laboratory adaptation effects on sleep. No significant differences were found when Night 2 recordings were compared to Night 1 in (1) sleep continuity measures of sleep efficiency and sleep latency to Stages 1, 2, Delta, and I-REM; (2) sleep architecture measures of time and percentage of sleep period time in Stages 1 and 2, and in the number of stage occurrences; and (3) sleep quality measures across the sleep period. Sleep continuity measures of wake and latency to REM were significantly different for the two nights, as were sleep architecture measures of time and percentage of sleep period time (SPT) spent in Stage Delta and REM. These findings support previous studies that suggest attenuation of FNE in home-like environments. This study also emphasizes the need for research to evaluate sleep adaptation patterns in the elderly.