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. Author manuscript; available in PMC: 2017 Jun 1.
Published in final edited form as: Neurobiol Aging. 2016 Mar 19;42:142–149. doi: 10.1016/j.neurobiolaging.2016.03.008

Figure 2.

Figure 2

Sleep fragmentation in aging is specific to slow wave sleep. Continuity of sleep manifested by survival curves (cumulative probability distributions) of stage-specific sleep runs in older (black) and younger (white) subjects. No significant difference between subjects was observed in the survival curves for REM (A), NREM 1 (B), or NREM 2 (C) sleep. The survival curve for older subjects showed a significant shift toward shorter runs of NREM 3 (slow wave) sleep compared with younger subjects, p < 0.001, log rank test (D). SWS = slow wave sleep.