Emotional working memory in older adults after total sleep deprivation

• Introduction: Even though the occurrence of sleep problems increases with age, few studies have focused on the cognitive effects of acute sleep deprivation in elderly. Most previous research indicate that, compared to young, older adults show less impairment in e.g. attention after sleep deprivation. However, little is known of whether the same pattern holds for higher cognitive functions. In addition, while old age is usually related to a general decrease in working memory abilities, performance on working memory tasks may differ depending on the emotional valence of the stimuli, where positive stimuli seem to be beneficial for working memory performance in older adults. The aim of the present study was to investigate the effect of sleep deprivation on emotional working memory in older adults using two levels of working memory load.Materials and methods: A healthy sample of 48 old adults (MAge=66.69 years, SDAge=3.44 years) was randomized into a total sleep deprivation group (TSD; n=24) or a sleep control group (SC; n=24). They performed a working memory task (n-back) containing positive, negative and neutral pictures in a low (1-back) and a high (3-back) working memory load condition. Performance was measured as Accuracy (d'), Omissions and Reaction Time (RT).Results: For the d' and Omissions we performed two separate 2x2x3 (sleep, working memory load, valence) repeated measures analyses of variance (rmANOVA). For the RTs, we applied a mixed-effects model. For both d' and RT we found no effect of sleep deprivation (Ps > .05). For valence, we found main effects on both d' (F1,46 = 5.56, P=.005) and RT (F1,95.7 = 4.84, P=.01). d' did not differ for positive and neutral pictures, but was in both cases significantly better than for negative pictures. RTs were significantly faster for positive pictures. However, a working memory load∗valence interaction (F1,95.7 = 4.50, P=.01) further revealed an effect of valence in the low, but not in the high load condition. In the low load condition, RTs were faster for positive than for neutral pictures and faster for neutral than for negative pictures. There was no significant effect of Omissions.Conclusions: Our results showed that emotional working memory performance was not significantly affected by one night of sleep deprivation in older adults, which contrast what we found in a sample of young adults from the same project. In line with previous research, our results indicate a beneficial effect of positive stimuli on working memory in older adults. This effect was present in both groups and most pronounced for reaction times in the condition with a lower cognitive demand. We can conclude that, among older adults, the working memory performance is not impaired by sleep deprivation and that the benefits of positive stimuli on working memory seem intact. These findings contribute to a better understanding of older adults' cognitive functioning after sleep deprivation.

Ämnesord

SAMHÄLLSVETENSKAP  -- Psykologi (hsv//swe)

SOCIAL SCIENCES  -- Psychology (hsv//eng)

Nyckelord

working memory

older adults

sleep deprivation

Psychology

psykologi

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