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. Author manuscript; available in PMC: 2007 Dec 1.
Published in final edited form as: Neurobiol Aging. 2005 Nov 23;27(12):1870–1879. doi: 10.1016/j.neurobiolaging.2005.10.011

Figure 2.

Figure 2

Average sleep times and circadian phase markers for the young and older subjects. The interval between sleep onset and sleep offset, measured by actigraphy on the week prior to admission, is depicted by the gray bar. The timing of Tmin (▼) and melatonin midpoint on the baseline night (■) and on the night following the light exposure (□) are indicated. The global timing of sleep (onset and offset) and circadian phase markers (DLMO 50%, melatonin midpoint, DLMOff 50%, Tmin) at baseline was earlier in the older adults (p = 0.052). The phase angles between the circadian phase markers and the timing of sleep were not different for the two groups.