108 research outputs found
Dynamics of Sleep-Wake Transitions During Sleep
We study the dynamics of the awakening during the night for healthy subjects
and find that the wake and the sleep periods exhibit completely different
behavior: the durations of wake periods are characterized by a scale-free
power-law distribution, while the durations of sleep periods have an
exponential distribution with a characteristic time scale. We find that the
characteristic time scale of sleep periods changes throughout the night. In
contrast, there is no measurable variation in the power-law behavior for the
durations of wake periods. We develop a stochastic model which agrees with the
data and suggests that the difference in the dynamics of sleep and wake states
arises from the constraints on the number of microstates in the sleep-wake
system.Comment: Final form with some small corrections. To be published in
Europhysics Letters, vol. 57, issue no. 5, 1 March 2002, pp. 625-63
Effects of sleep deprivation on neural functioning: an integrative review
Sleep deprivation has a broad variety of effects on human performance and neural functioning that manifest themselves at different levels of description. On a macroscopic level, sleep deprivation mainly affects executive functions, especially in novel tasks. Macroscopic and mesoscopic effects of sleep deprivation on brain activity include reduced cortical responsiveness to incoming stimuli, reflecting reduced attention. On a microscopic level, sleep deprivation is associated with increased levels of adenosine, a neuromodulator that has a general inhibitory effect on neural activity. The inhibition of cholinergic nuclei appears particularly relevant, as the associated decrease in cortical acetylcholine seems to cause effects of sleep deprivation on macroscopic brain activity. In general, however, the relationships between the neural effects of sleep deprivation across observation scales are poorly understood and uncovering these relationships should be a primary target in future research
Circuit-based interrogation of sleep control.
Sleep is a fundamental biological process observed widely in the animal kingdom, but the neural circuits generating sleep remain poorly understood. Understanding the brain mechanisms controlling sleep requires the identification of key neurons in the control circuits and mapping of their synaptic connections. Technical innovations over the past decade have greatly facilitated dissection of the sleep circuits. This has set the stage for understanding how a variety of environmental and physiological factors influence sleep. The ability to initiate and terminate sleep on command will also help us to elucidate its functions within and beyond the brain
Minutes of Group 61 - Group 64 Meeting, 8 September 1954
At a meeting held between representatives of Groups 61 and 64, use of WWI's magnetic tape and camera facilities by programmers and computer operators was discussed. Group 61 agreed to correct several deficiencies in its use of magnetic tapes, particularly when tapes are used for delayed printout. Both Groups will investigate means of improving the camera facilities
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