The insomnia of 'sleeping in a strange place': effects of l-tryptophane

Forty-two normal human subjects were studied in the sleep laboratory for one night each. Fourteen were given placebo at bedtime, 14 took l-tryptophane 1 g, and 14 took l-tryptophane 3 g. Both tryptophane groups had significantly lower sleep latency than the placebo group. The usually discarded 'first laboratory night' produces a mild situational insomnia in normal persons and thus can be useful in certain sleep studies.