Non-rapid eye movement sleep

About: Non-rapid eye movement sleep is a research topic. Over the lifetime, 8661 publications have been published within this topic receiving 389465 citations. The topic is also known as: NREM.

Coordinated infraslow neural and cardiac oscillations mark fragility and offline periods in mammalian sleep.

Abstract: Rodents sleep in bouts lasting minutes; humans sleep for hours. What are the universal needs served by sleep given such variability? In sleeping mice and humans, through monitoring neural and cardiac activity (combined with assessment of arousability and overnight memory consolidation, respectively), we find a previously unrecognized hallmark of sleep that balances two fundamental yet opposing needs: to maintain sensory reactivity to the environment while promoting recovery and memory consolidation. Coordinated 0.02-Hz oscillations of the sleep spindle band, hippocampal ripple activity, and heart rate sequentially divide non–rapid eye movement (non-REM) sleep into offline phases and phases of high susceptibility to external stimulation. A noise stimulus chosen such that sleeping mice woke up or slept through at comparable rates revealed that offline periods correspond to raising, whereas fragility periods correspond to declining portions of the 0.02-Hz oscillation in spindle activity. Oscillations were present throughout non-REM sleep in mice, yet confined to light non-REM sleep (stage 2) in humans. In both species, the 0.02-Hz oscillation predominated over posterior cortex. The strength of the 0.02-Hz oscillation predicted superior memory recall after sleep in a declarative memory task in humans. These oscillations point to a conserved function of mammalian non-REM sleep that cycles between environmental alertness and internal memory processing in 20- to 25-s intervals. Perturbed 0.02-Hz oscillations may cause memory impairment and ill-timed arousals in sleep disorders.

The two faces of Eve Dopamine’s modulation of wakefulness and sleep

Abstract: In Parkinson's disease (PD), waking is frequently punctuated by sleep episodes, including rapid eye movement (REM) (i.e., dream) sleep, and sleep is interrupted by motor activities such as periodic limb movements and REM sleep behavior disorder. Because these pathologic behaviors are unaccounted for by contemporary models, this review summarizes the complex effects of dopamine (DA) on normal and pathological waking-sleeping. Maintenance of wakefulness is probably promoted by mesocorticolimbic DA circuits, and suppression of nocturnal movement appears to be influenced by indirect pathways linking midbrain DA neurons with pre-motor structures in the mesopontine tegmentum and ventromedial medulla. A diencephalospinal DA system may have an additional important role in mediating state-specific sensorimotor activity that is relevant to periodic limb movements and restless legs syndrome.

Memory for semantically related and unrelated declarative information: the benefit of sleep, the cost of wake.

Abstract: Numerous studies have examined sleep's influence on a range of hippocampus-dependent declarative memory tasks, from text learning to spatial navigation. In this study, we examined the impact of sleep, wake, and time-of-day influences on the processing of declarative information with strong semantic links (semantically related word pairs) and information requiring the formation of novel associations (unrelated word pairs). Participants encoded a set of related or unrelated word pairs at either 9am or 9pm, and were then tested after an interval of 30 min, 12 hr, or 24 hr. The time of day at which subjects were trained had no effect on training performance or initial memory of either word pair type. At 12 hr retest, memory overall was superior following a night of sleep compared to a day of wakefulness. However, this performance difference was a result of a pronounced deterioration in memory for unrelated word pairs across wake; there was no sleep-wake difference for related word pairs. At 24 hr retest, with all subjects having received both a full night of sleep and a full day of wakefulness, we found that memory was superior when sleep occurred shortly after learning rather than following a full day of wakefulness. Lastly, we present evidence that the rate of deterioration across wakefulness was significantly diminished when a night of sleep preceded the wake period compared to when no sleep preceded wake, suggesting that sleep served to stabilize the memories against the deleterious effects of subsequent wakefulness. Overall, our results demonstrate that 1) the impact of 12 hr of waking interference on memory retention is strongly determined by word-pair type, 2) sleep is most beneficial to memory 24 hr later if it occurs shortly after learning, and 3) sleep does in fact stabilize declarative memories, diminishing the negative impact of subsequent wakefulness.