Sleep deprivation and affective dynamics

Objectives:
The aim of this study was to evaluate diurnal variation in positive and negative emotion
and the impact of 28 hours of sleep deprivation on emotional experience.

Methods:
Subjects
Young healthy sleepers (mean age 24y, SD = 6, preliminary N = 15) were selected for the
purpose of this study.

Materials and procedure
After an adaptation and baseline night (8 hours time in bed), subjects were kept awake for 28 hours in controlled laboratory conditions. Affective dynamics were evaluated by 4 hourly assessment of the extended version of the Positive and Negative Affect Schedule (PANAS-X; Watson & Clark, 1994) with a focus on relevant emotion components, respectively Positive (PA) and Negative Affect (NA), the basic emotions of Fear, Hostility, Guilt, Sadness, Joviality, Self-Assurance and Attentiveness and the affective state of Fatigue.

Analyses
Repeated-measures analyses of variance (ANOVA) with time of day (from 10h day 1 to 10h day 2) as repeated measure were performed for the different emotion components. Contrasts were used to look more closely into significant time of day variations.

Results:
Preliminary results indicate a relative stable manifestation of general NA even after 28h of sleep deprivation, F(3.279,45.907) = 1.276, ns. For PA a significant variability was observer over time, F(6,78) = 19.323, p
Furthermore a general decrease in all basic positive emotions was found over the sleep deprivation period, respectively F Joviality(6,84) = 914.612, p
Regarding the basic negative emotion scales, a general stability was found regarding the emotions of fear and guilt, respectively F Fear(3.455,48.374) = .728, ns and F Guilt(2.413,33.788) = .861, ns. A trend was found regarding hostility, F(2.085, 29.189) = 2.485, p
Conclusion:
In line with previous research, a diurnal stability of general negative affect was found. However the sharp rise in positive emotion from morning till noon, was not replicated in this study (Clark, Watson & Leeka, M&E, 1989). Yet, a clear effect of sleep deprivation on general positive affect was observed. Subjects showed a decrease in all basic positive emotions, starting in the early night period, with a stabilization throughout the further sleep deprivation period. Regarding the basic negative emotion components, the effect seems to be less determined. During the whole sleep deprivation period, an emotional stability has been observed for the basic emotions of guilt and surprisingly, against earlier evidence, of fear (Sagaspe et al., B&C, 2006). However, together with the expected night-time increase in fatigue (Durmer & Dinges, SiN, 2005), an evening rise in sadness and a night-time increase in hostility has been observed, all followed by a relative stability during the further sleep deprivation period. These results indicate a selective change in emotional experience instead of an overall change in affect with increasing sleep deprivation, an important finding to be further investigated with relevant societal and clinical implications.