A polysomnographic study of sleep patterns in normal humans with low- or high-anxiety personality traits

To clarify the effects of anxiety-related personality traits on sleep patterns, polysomnographic examinations (PSG) were performed over 4 consecutive nights on normal humans who tested within the low- or high-anxiety ranges. The subjects consisted of two groups of six male university students who scored either less than 45 points (low-anxiety group) or more than 55 points (high-anxiety group) on the Spielberger's State Trait Anxiety Inventory. Compared to the levels of sleep change in the high-anxiety group, the low-anxiety group exhibited a greater change in REM sleep and stage 2 sleep. The REM sleep in the low-anxiety group was shorter on the first and second nights compared to the third and fourth nights, and the stage 2 sleep was longer on the first night than on the remaining three nights. Thus, the low-anxiety group showed a first-night effect followed by partial recovery on the second night, while the high-anxiety group exhibited no obvious first-night effect. These results suggest that there is a difference in sleep patterns, assessed by consecutive PSG, between those with low- and high-anxiety traits, and that anxiety-related personality traits attenuate the occurrence of the first-night effect, reflecting a lower adaptability to a novel environment.