Daytime naps improve procedural motor memory
ABSTRACT To investigate the impact of a short daytime nap on procedural and declarative memory consolidation.
Following a normal night's sleep, 34 young healthy subjects were randomly assigned to a nap or wake condition of about 45min in the early afternoon after learning procedural and declarative memory tasks. Subjects were controlled for alertness and cortisol secretion.
The afternoon naps were dominated by sleep stage 2 but contained some slow wave sleep (SWS) and rapid eye movement (REM) sleep as well. Naps significantly improved procedural, but not declarative, memory. Females showed more improvement than males in the declarative memory tasks irrespective of nap or wake. There was no difference between groups with respect to cortisol secretion or alertness.
A short nap is favorable for consolidation of procedural memory. The possibly confounding effect of gender should always be considered in research on sleep and memory.
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ABSTRACT: 30 college students who have the habit of lunch time napping (LTN) participated in experiments under two different conditions: Having lunch time napping and not having lunch time napping. They were asked to complete three tasks in-cluding vigilance reaction, short-term memory, addition arithmetic; their performance was re-corded automatically by computer during 3 dif-ferent periods in the afternoon and early eve-ning. The analysis about the experimental data showed that: as for habitual nappers, midafter-noon nap zone existed, LTN played a very im-portant role in overcoming it, and did great help in enhancing their vigilance in the afternoon and early evening, however, LTN didn't bring sig-nificant positive effect to executing complex tasks (such as short-term memory and addition task) at the periods of time 16:30-17:30, 20:00-21:00. Finally, this article discussed the conclu-sions and its significance.
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ABSTRACT: Many young females take exogenous hormones as oral contraceptive (OC), a condition rarely controlled for in studies on sleep and memory consolidation even though sex hormones influence consolidation. This study investigated the effects of OCs on sleep-related consolidation of a motor and declarative task, utilizing a daytime nap protocol. Fifteen healthy, young females taking OCs came to the sleep lab for three different conditions: nap with previous learning, wake with previous learning and nap without learning. They underwent each condition twice, once during the 'pill-active' weeks and once during the 'pill-free' week, resulting in 6 visits. In all conditions, participants showed a significant off-line consolidation effect, independent of pill week or nap/wake condition. There were no significant differences in sleep stage duration, spindle activity or spectral EEG frequency bands between naps with or without the learning condition. The present data showed a significant off-line enhancement in memory irrespective of potential beneficial effects of a nap. In comparison to previous studies, this may suggest that the use of OCs may enhance off-line memory consolidation in motor and verbal tasks per se. These results stress the importance to control for the use of OCs in studies focusing on memory performance. © 2015 S. Karger AG, Basel.Neuropsychobiology 02/2015; 70(4):253-261. DOI:10.1159/000369022 · 2.30 Impact Factor
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ABSTRACT: Alpha/theta neurofeedback training is supposed to enhance cognitive performance as well as alleviate psychiatric disorders. Sleep during this training is regarded a confounding factor, although it is usually not controlled. Here, the amount of sleep, the impact of sleep on frequency results and the validity of subjective judgments of having fallen asleep were investigated. 40 healthy young subjects participated in 31 training units of real or mock feedback. It turned out that stage 2 sleep occurred in 10-14 % of training time, in 95 % of the subjects and in 1/3 of all training units. Sleep significantly influenced the theta/alpha ratio and theta but not alpha amplitudes. Only about 2/3 of the subjective judgements were correct and no more than 13 % of the participants could reliably identify sleep. These data demonstrate that sleep can easily occur during alpha/theta neurofeedback training and should be controlled by objective means.Applied Psychophysiology and Biofeedback 04/2015; DOI:10.1007/s10484-015-9278-9 · 1.13 Impact Factor