clock will work with day and night schedules even when you try to change it. Those who work night shifts still feel naturally sleepy when night time comes. This also occurs with jet lag. The conflict, set up by trying to be active during the brain's biological night time can lead to decreased cognitive and motor skills. Shift workers with changeable hours usually start to suffer with a sleep debt. Those who are active every night need to retrain their biological clock with light cues. " Adults need less sleep as they grow older" Older people do not need less sleep, but they often get less. The ability to sleep for long periods and get into the deep rest full stages of sleep gets harder as we get older. The older we get the more 'fragile ' our sleep and we are more easily disturbed by light, noise, and PAIN.