The role of sleep and wakefulness in the recognition of emotional pictures

Abstract

Sleep has a beneficial effect on memory consolidation. However, its role in emotional memory is currently debated. Here, we investigate the role of sleep and a similar period of wakefulness on the recognition of emotional pictures and subjective emotional reactivity. Forty participants without any major physical, neurological or psychological condition were randomly assigned to the Sleep First Group or Wake First Group. The two groups underwent the encoding phase of an emotional images task with negative and neutral pictures at either 09:00 hours (Wake First Group) or 21:00 hours (Sleep First Group). Then participants performed an immediate recognition test (T1), and two delayed tests 12 hr (T2) and 24 hr (T3) later. Perceived arousal and valence levels were collected for each picture. Sleep parameters were recorded at participants' homes with a portable device. No differences were observed at T1, whereas at T2 the Sleep First Group showed a higher memory performance than the Wake First Group. At T3, performance decreased in the Sleep First Group (who spent the previous 12 hr awake), but not in the Wake First Group (who slept during the previous 12 hr). Overall, negative images were remembered better than neutral ones. We also observed a positive association between memory performance for negative items at the immediate test and the percentage of rapid eye movement sleep the night before the encoding. Our data confirm that negative information is remembered better over time than neutral information, and that sleep benefits the retention of declarative information. However, sleep seems not to preferentially improve emotional memory, although it may affect the encoding of negative information.

The Effect of One Night of Sleep on Mnemonic Discrimination of Emotional Information

“…While the content is preserved over periods of sleep, the affective tone should start to decline after a sleep period. However, it is in line with the idea that sleep tends to preserve the emotional reactivity associated with an emotional event [ 49 ] and in line with previous empirical studies using subjective reports [ 50 , 51 , 52 , 53 , 54 ]. Interestingly, the current sample showed no difference in terms of arousal for neutral and positive stimuli.…”

Investigating the effects of sleep and sleep loss on the different stages of episodic emotional memory: A narrative review and guide to the future

“…As noted above, the sleep effect was strongly diminished in the wake-first group compared to the sleep-first condition, suggesting that sleep may have less of an impact on emotional memory processing once the memory reaches this stage, at least for some paradigms. A final study recently utilized a similar sleep-first vs. wake-first protocol, but memory was tested for negative and neutral scenes on three separate occasions across the protocol: immediately following encoding, 12-h after encoding, and 24-h after encoding ( Carollo et al, 2022 ). While immediate testing showed no differences, at the 12-h mark memory was clearly benefited by a sleep period, though this effect was generalized and not limited to negative pictures.…”

“…While immediate testing showed no differences, at the 12-h mark memory was clearly benefited by a sleep period, though this effect was generalized and not limited to negative pictures. Interestingly, testing after the 24-h delay showed that the sleep-first group showed deterioration in memory in the subsequent 12-h of wakefulness, while memory was largely preserved from the 12- to 24-h test in the wake-first group after receiving their opportunity for sleep in the second half of the protocol ( Carollo et al, 2022 ). Importantly, while the authors clearly state that the intention was to assess delayed sleep-dependent consolidation on emotional memory, it is likely that the 12-h testing session reactivated memory traces for the stimuli that had been set aside for the 24-h assessment.…”