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To sleep, to strive, or both: how best to optimize memory.

Tucker MA, Tang SX, Uzoh A, Morgan A, Stickgold R - PLoS ONE (2011)

Bottom Line: Over an extended 24 hr interval we found 1) that an initial night of sleep partially protects memories from subsequent deterioration during wake, and 2) that sleep blocks further deterioration, and may even have a restorative effect on memory, when it follows a full day of wake.Interestingly, the benefit imparted to rewarded (relative to unrewarded) stimuli was equal for sleep and wake subjects, suggesting that the sleeping brain may not differentially process rewarded information, relative to wake.However, looking at the overall impact of sleep relative to reward in this protocol, it was apparent that sleep both imparted a stronger mnemonic boost than reward, and provided a benefit to memory regardless of whether it occurred in the first or the second 12 hrs following task training.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, United States of America. mtucker1@bidmc.harvard.edu

ABSTRACT
While numerous studies have shown that a night of sleep profits memory relative to wake, we still have little understanding about what factors mediate this effect of sleep. A clear understanding of the dynamics of this effect of sleep beyond the initial night of sleep is also lacking. Here, we examined the effect of extrinsic rewards on sleep-dependent declarative memory processing across 12 and 24 hr training-retest intervals. Subjects were either paid based on their performance at retest ($1 for each correct answer), or received a flat fee for participation. After a 12 hr interval we observed pronounced benefits of both sleep and reward on memory. Over an extended 24 hr interval we found 1) that an initial night of sleep partially protects memories from subsequent deterioration during wake, and 2) that sleep blocks further deterioration, and may even have a restorative effect on memory, when it follows a full day of wake. Interestingly, the benefit imparted to rewarded (relative to unrewarded) stimuli was equal for sleep and wake subjects, suggesting that the sleeping brain may not differentially process rewarded information, relative to wake. However, looking at the overall impact of sleep relative to reward in this protocol, it was apparent that sleep both imparted a stronger mnemonic boost than reward, and provided a benefit to memory regardless of whether it occurred in the first or the second 12 hrs following task training.

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Study design.
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pone-0021737-g001: Study design.

Mentions: In this study, we also examined memory performance when sleep occurred in either the first or second half of the 24 hr period (see Figure 1). This analysis is critical because, even though recall of declarative (fact-based) information is superior following a night of sleep compared to an equal period of daytime wake [7], [9], it is unclear, using a 12 hr training-retest interval, whether sleep has to closely follow training or whether it can benefit memory when it occurs more than 12 hrs after training (i.e., after a full day of wake). One study thus far reports that performance on a spatial memory task (face-location associations), at 24 hr retest, benefits from sleep when sleep closely follows training, but not when 12 hrs of wake are interposed between training and sleep [10]. Another study has demonstrated the same effect for vocabulary learning [11]. However, a third study, using a word pair learning task with children 9–12 yrs of age, showed similar sleep benefits regardless of whether sleep occurred during the first or second 12 hrs of the training-retest interval [12].


To sleep, to strive, or both: how best to optimize memory.

Tucker MA, Tang SX, Uzoh A, Morgan A, Stickgold R - PLoS ONE (2011)

Study design.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3140493&req=5

pone-0021737-g001: Study design.
Mentions: In this study, we also examined memory performance when sleep occurred in either the first or second half of the 24 hr period (see Figure 1). This analysis is critical because, even though recall of declarative (fact-based) information is superior following a night of sleep compared to an equal period of daytime wake [7], [9], it is unclear, using a 12 hr training-retest interval, whether sleep has to closely follow training or whether it can benefit memory when it occurs more than 12 hrs after training (i.e., after a full day of wake). One study thus far reports that performance on a spatial memory task (face-location associations), at 24 hr retest, benefits from sleep when sleep closely follows training, but not when 12 hrs of wake are interposed between training and sleep [10]. Another study has demonstrated the same effect for vocabulary learning [11]. However, a third study, using a word pair learning task with children 9–12 yrs of age, showed similar sleep benefits regardless of whether sleep occurred during the first or second 12 hrs of the training-retest interval [12].

Bottom Line: Over an extended 24 hr interval we found 1) that an initial night of sleep partially protects memories from subsequent deterioration during wake, and 2) that sleep blocks further deterioration, and may even have a restorative effect on memory, when it follows a full day of wake.Interestingly, the benefit imparted to rewarded (relative to unrewarded) stimuli was equal for sleep and wake subjects, suggesting that the sleeping brain may not differentially process rewarded information, relative to wake.However, looking at the overall impact of sleep relative to reward in this protocol, it was apparent that sleep both imparted a stronger mnemonic boost than reward, and provided a benefit to memory regardless of whether it occurred in the first or the second 12 hrs following task training.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, United States of America. mtucker1@bidmc.harvard.edu

ABSTRACT
While numerous studies have shown that a night of sleep profits memory relative to wake, we still have little understanding about what factors mediate this effect of sleep. A clear understanding of the dynamics of this effect of sleep beyond the initial night of sleep is also lacking. Here, we examined the effect of extrinsic rewards on sleep-dependent declarative memory processing across 12 and 24 hr training-retest intervals. Subjects were either paid based on their performance at retest ($1 for each correct answer), or received a flat fee for participation. After a 12 hr interval we observed pronounced benefits of both sleep and reward on memory. Over an extended 24 hr interval we found 1) that an initial night of sleep partially protects memories from subsequent deterioration during wake, and 2) that sleep blocks further deterioration, and may even have a restorative effect on memory, when it follows a full day of wake. Interestingly, the benefit imparted to rewarded (relative to unrewarded) stimuli was equal for sleep and wake subjects, suggesting that the sleeping brain may not differentially process rewarded information, relative to wake. However, looking at the overall impact of sleep relative to reward in this protocol, it was apparent that sleep both imparted a stronger mnemonic boost than reward, and provided a benefit to memory regardless of whether it occurred in the first or the second 12 hrs following task training.

Show MeSH