The structure of mood: A comparison between sleep deprivation and normal wakefulness conditions

Summary The stability of the factor structure of mood was examined under two different experimental conditions, sleep deprivation and normal wakefulness In the first phase of the study, two different forms of a mood scale were administered to several college classes, and the ratings for each scale were intercorrelated and factored Eight interpretable factors emerged from each analysis, and the two sets of factors were highly congruent. In the second phase of the study subjects completed the mood ratings after staying awake all night or after getting a good night's rest Comparisons between the means for the two groups showed significant differences on 26 of the 44 variables included in the scale The scores for the sleep‐deprived group were then intercorrelated and factored, and the factor structure was compared with the relevant factor structure obtained in the first phase of the study The results of the comparison showed that six of the eight factors appeared under both conditions of sleep deprivation and normal wakefulness Additional analysis indicated that a seventh factor appeared, but in the guise of different variables The only factor which failed to appear under sleep deprivation was elation. It was concluded that although variable ratings showed high sensitivity to the experimental operations, the basic structure of the underlying mood states remained remarkably stable The results indicate that the search for a list of basic mood states may be quite fruitful An important methodological implication was that a variable may be selected to measure a mood under various experimental operations with the assurance that the nature of the mood to be measured does not change as a result of those operations