An activity monitor study on the sleep‐wake rhythm of healthy aged people residing in their homes

The aim of this preliminary study was to investigate sleep‐wake rhythm in active, healthy elderly people residing in their usual habitat. The subjects were thirty‐five male volunteers within an age range of 65–95 for 3–4 days. We measured the sleep‐wake rhythm of the subjects with an Actillume® which is a combined wrist activity monitor and illumination recorder. Analysis of the Actillume® recording showed that 24 of the 35 subjects (69%) kept continuous activity indicating good maintenance of wakefulness with high light exposure. The mean mesor of sleep‐wake rhythm, however, significantly decreased in the older subjects (aged 80–95; n= 15).