Reverse first night effect in insomnia.

This study evaluates the reverse first night effect (FNE) in insomniacs. All insomniacs evaluated at the Dartmouth Sleep Disorders Center between 1975 and 1980 were studied if they met specific criteria (n = 89). First night effects were assessed using the following four variables: sleep efficiency, sleep latency, percentage of rapid eye movement (REM) sleep, and REM latency. The 20 subjects who showed the strongest normal FNE were compared with the 20 showing the strongest reverse FNE. The two groups were similar in age, sex, and most aspects of reported home sleep. They differed in their sleep on night 1, but on nights 2 and 3 their sleep was quite similar. Both groups overestimated their sleep latencies on night 1 (by subjective reports) but unlike the normal FNE group, the reverse FNE patients very accurately assessed their sleep latency on nights 2 and 3. Reverse FNE patients had significantly higher scores than normal FNE patients on the Minnesota Multiphasic Personality Inventory (MMPI) K (defensiveness, guardedness) and Pa (paranoia) scales, and they were less depressed, marginally less anxious, and somewhat more sensation-seeking and more susceptible to boredom. This study concluded that evaluations using only 1 night in the laboratory may be missing the larger picture of a patient's insomnia. When data from only 1 laboratory night are available for an insomniac, care should be taken with the label of "subjective complaint without objective findings" in patients who are defensive, guarded, and sensation-seeking.