Lithium effects on time estimation and mood in manic-melancholic patients. A study of diurnal variations.

Behavioural measurements of time experience and phenomenological self-ratings of mood-variations (Beecher's Mood Scale) have been carried out at night and on the following morning in a group of lithium-treated patients, in a group of psychiatric patients not given lithium, and in an untreated group of healthy subjects. In all the groups investigated the internal "clock" was slower in the morning than in the night. The results indicated that the internal "clock" in lithium-treated patients was slower than in the two other groups, but only at night. Mood variations from night ot morning were observed in all three groups. The group of lithium-treated patients had fewer complaints as to self-report of mood-variations compared with the other groups.