Abstract
Introduction
Sleep difficulties, such as insomnia, are highly prevalent in individuals with Post-Traumatic Stress Disorder (PTSD). However, sleep deprivation can also increase emotional reactivity to positive (as well as negative) stimuli. While the effects of sleep loss on emotional perception healthy individuals has been documented, it remains unclear how lack of sleep in individuals with PTSD may affect their emotional reactivity to positive stimuli. We hypothesized that lower habitual sleep duration would be associated with greater functional brain activation changes in response to subliminally presented happy faces in brain areas of the reward network, such as the rostral anterior cingulate cortex (rACC).
Methods
Thirty-nine individuals with DSM-5 confirmed PTSD were administered the Pittsburgh Sleep Quality Index (PSQI) as a measure of their average nightly sleep duration over the past month. Participants then underwent fMRI imagining while viewing subliminal presentations of faces displaying happiness, using a backward masked facial affect paradigm to minimize conscious awareness of the expressed emotion. Brain activation to masked happy expressions was regressed against sleep duration in SPM12.
Results
There was a negative correlation between habitual sleep duration and activation within the rACC in response to the masked happy faces (x=14,y=40,z=0; k=102, pFWE-corr= 0.008).
Conclusion
Individuals with PTSD who average less sleep at night showed greater emotional reactivity, as indexed by greater functional brain activation changes within an area of the reward network, than individuals who obtained more sleep per night. Future research involving actual sleep duration manipulation will be necessary to determine whether this finding reflects the well-known antidepressant effect of sleep deprivation or a form of greater emotional expression error monitoring among traumatized patients when lacking sleep. Regardless, these findings suggest that insufficient sleep could affect unconsciously perceived emotion in faces and potentially affect social and emotional responses among individuals with PTSD.
Support
US Army Medical Research and Materiel Command: W81XWH-14-1-0570
Shorter sleep duration is associated with lower GABA levels in the anterior cingulate cortex
