The organization of rapid eye movement activity during rapid eye movement sleep is impaired in the elderly

Rapid eye movement activity (REMA) during rapid eye movement activity (REM) sleep was studied in eight elderly subjects and six young adults as a cont rol group. Beyond global quantitative features (REMA density), we evaluated the organizational aspects of REMA, that is its occurrence in burst mode, still largely unknown in the aged. REMA density in the elderly is not signi ficantly different than that of young adults. By contrast, the duration of REMA bursts is reduced iii the elderly, as well as the 'burst state-to-burs t-state' probability, i.e. the probability for successive inter-REMA time i ntervals to be part of the same REMA burst. These results show that global aspects of the quantitative features of REMA are preserved in the elderly, whereas their organizational aspects are impaired. These data are consisten t with the hypothesis that aging is associated with a difficulty in maintai ning physiological processes over time. (C) 1999 Elsevier Science Ireland L td. All rights reserved.