Sleep plays a critical role in the consolidation of emotional memory. Sleep disruptions are also linked to emotion dysregulations and, in long-term, affective disorders. This study investigates how targeted modifications of Slow Wave sleep (SWS) and Rapid-Eye Movement (REM) sleep, induced by an antidepressant (Reboxetine, RBX) and a narcolepsy treatment (Sodium Oxybate, SXB), affect emotional episodic memory.

Nineteen healthy men participated in a within-subject, double-blind, randomized, placebo-controlled protocol. Participants were asked to rate emotional images (negative, neutral and funny) while functional Magnetic Resonance Imaging (fMRI) recordings were made of their brain activity. After drug uptake, they were allowed to sleep at the lab under polysomnography recordings. The next day, participants had to retrieve the old images and discriminate them from new neutral and emotional ones.

Our findings reveal that acute drug administration significantly alters sleep macro and micro architecture. Specifically, REM sleep duration was significantly decreased for both drugs while NREM sleep was enhanced. The relative sigma power was increased following RBX uptake. Subsequently, RBX reduced the positive impact of emotion on memory and altered the natural positive shift of valence ratings for negative images. At the brain level, the specificity of amygdala activation for negative pictures is decreased under RBX. While the hippocampal region is less capable of distinguishing new items under SXB, we do not observe a difference in memory performance.

These results underscore the importance of the different sleep stages and associated neurotransmitter changes in emotional processing, and reenforce potential therapeutic targets of sleep for affective disorders.