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. Author manuscript; available in PMC: 2009 Oct 20.
Published in final edited form as: J Am Geriatr Soc. 2002 Feb;50(2):282–289. doi: 10.1046/j.1532-5415.2002.50060.x

Figure 1.

Figure 1

Raw data and model fit for one subject before and during morning light therapy. Raw data are plotted as small dots, the traditional cosine curve is plotted as a wide, smooth line, and the extended model is plotted as a thin, dotted line. The pretreatment activity data (left-hand panel) seem to have no rhythm. The peaks of the curve clearly do not match the peaks in the data. The activity data in the treatment phase (right-hand panel) are clearly more rhythmic. The extended cosine model is clearly a better representation of the data than the cosine model. For this subject, activity rhythmicity improved after treatment, and the activity acrophase estimate shifted to a later time after treatment.