Effects of Depressed Affect on Diurnal and Ultradian Variations in Mood in a Healthy Sample

The study investigated diurnal and ultradian variations in cheerful and depressed mood in a healthy sample, and examined whether these variations were related to severity of depressed affect. Thirty employed volunteers used a pocket computer to complete self-rating scales of depression and cheerfulness every 2 h for 14 days except during sleep periods. They also completed the Beck Depression Inventory (BDI) and the General Health Questionnaire (GHQ). Analysis of variance of depressed mood showed a significant interaction between time of day and BDI/GHQ, in which only the mood of the high BDI/GHQ groups got worse during the day. The low BDI group showed a diurnal variation in cheerful mood in which mood was at its best in the early evening. Cosinor and “binfit” analysis of raw and residual time-series showed that more than half of the participants had significant fitting ultradian rhythms in mood in the range 3-9 h. However, only the number of significant fits for residual cheerful mood was substantially above the level of chance. The amplitudes of the ultradian rhythms in raw depressed mood were greater in participants scoring higher on the BDI/GHQ scales, but this seemed to reflect an increase in serial dependency between depressed mood states. The results are discussed in relation to circadian rhythms in mood and depression.