The effect of napping on attentional bias to sad faces among people with depression

Objectives: Sleep problems, such as insomnia, is a predictor of depression, suggesting the role of sleep on affecting depression. Besides, previous study found that attentional bias to sad faces was found among depressed individual. However, there was no study investigating whether sleep could affect depression through its effects on attentional bias to sad stimuli. The aim of this study was to investigate the effect of napping on decreasing the attentional bias to sad faces among people with depression. Another purpose of this study was to explore the possible sleep architecture variables which contribute to such changes in attentional bias. Methods: There were total 51 Hong Kong participants aged between 22 to 60, 19 of them had depression and 32 of them were healthy, who were further randomly assigned to nap or wake condition. Participants first completed the pre-test of the dot-probe task which measured attentional bias. Afterwards, those in the nap group had 90-minute nap opportunity monitored by polysomnography (PSG) while those in wake group had to remain wakeful in the same period. The participants then completed the post-test of dot-probe task. Results: Results found that (1) attentional bias to sad faces is significantly decreased among depressed nap group, but remain the same level among other groups and (2) sleep stage 2 is positively correlated with decrease in attentional bias to sad faces among depressed group. Conclusion: This is the first study which suggests that sleep specifically decreases attentional bias among people with depression. The finding carries implication for the mechanism of sleep in affecting depression through attentional bias and the possible therapeutic effect of napping among depressed people. All rights reserved.