ABSTRACT
In another study, volunteers aged from 18 to 32 and from 60 to 75 slept fitted with wrist-worn activity-recorders [3]. The older did not spend less time in bed at night but woke up sooner and more often after they had first fallen asleep. Records of their 24-hour activity patterns suggest that they might have made up for any sleep that they lost during the night by napping during the day, particularly during the two hours before going to bed. Up to 42 per cent of the young adults also took daytime naps, but this did not seem to affect how long they slept at night. Those young who napped, typically did so in the early afternoon. Bright illumination in the late evening tended to delay the times that elderly people went to bed and also their first night-time awakenings. For those enduring dark northern winters, lamps that mimic the colour and intensity of sunshine and include ultra-violet radiation did help to maintain a regular sleep/wake cycle. For all elderly people, taking more exercise and losing weight reduced evening napping and delayed the first night-time awakening.
