From Web MD (www.webmd.com):
Why Does Grandpa Nap All Day?
By the time we reach our senior years, we may have more time for sleep — but once again, we’re not getting it.
There’s a general notion that the elderly need less sleep, but that may not be true, says Simpson, who’s just completed a review of the literature on sleep and aging.
“It turns out that they do get less sleep, but it’s not necessarily because they need less,” he says. “To some extent, their sleep is frustrated by all the issues of aging — a bad hip, a sore back, heart trouble, a knee that’s out of whack.”
Older people also have a tendency to develop something called advanced sleep-phase syndrome, in which the whole rhythm of their circadian clock is off.
“They go to bed much earlier in the evening and wake up much earlier in the morning,” Simpson says. “The system becomes deregulated and loose, and they kind of unlearn the rhythms of sleep.”
Basically, the elderly revert back to the sleep schedule and patterns of very young children.
“They also wake up many more times during the night than younger adults,” Chokroverty says. “This is why they take naps during the day.”
One way to treat this problem is with bright light therapy in the morning and early evening.