The first night effect revisited with age as a variable.

The EEG records of 15 younger females and 40 older females were analyzed in an effort to reevaluate the effects of the first night of laboratory sleep, and to determine to what extent age may be a variable in the First Night Effect. These records substantiate earlier findings that sleep latency is longer, there is more wakefulness, and the REM cycle is disrupted on the first night of laboratory sleep. In addition, there is some evidence that older subjects show a greater First Night Effect. These effects adapt out by the second night of sleep.