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

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