"Two to four hours would be possible only for a night or two for a healthy person before they were impaired during waking and crash into a deeper sleep the next night," said Rosalind Cartwright, chairman of the department of psychology at Rush University and author of the forthcoming book "The Twenty-Four Hour Mind." "It also reduces glucose tolerance and so makes one vulnerable to diabetes. Short sleep is associated with an increase in obesity, hypertension, diabetes and stroke."
There remains some controversy over whether people need less sleep as they get older. What is clear is that they tend to get less sleep with age.
It's not that people need less sleep as they age, but they have difficulty sustaining sleep for as long as they did when they were younger.
The number of hours of sleep may "decline some in old age only because sleep fragments with more awakenings at night and begins to intrude into catnaps during the day," said Cartwright. "The total hours in 24 is still the same."
While older people may need as much sleep as those who are younger, there is some defined difference when it comes to comparing people at the beginning of life.
"If you take a lifetime perspective, from cradle to grave, this is almost certainly true, as many infants get some 10- to 12-plus hours of sleep a day, and most elderly folks get some five to six hours," said Michael Perlis, director of the Penn Behavioral Sleep Medicine Program in an e-mail to ABCNews.com.
But assuming older people need less sleep because they don't sleep as much as they once did presents problems.
"It's a dangerous myth, because it leads one to dismiss sleep disorders that could be [treated] if they're addressed correctly in older adults," said Dr. Alon Avidan, associate director of the sleep disorders program at UCLA.
While there's no substitute for a good night's sleep, naps may provide a short-term solution to daytime sleepiness if doled out properly.
Avidan explained that power naps of 15 to 20 minutes in the early afternoon (1 to 3 p.m.) are best to help one feel refreshed.
Longer naps, he said, exceeding 45 minutes, can do just the opposite.
"The longer you nap, the more likely you are to wake up from deep sleep," he said, leading you to feel confused and groggy.
Napping too late in the day can lead to insomnia, as it may shift your body's rhythms.
"If you sleep then, the tendency would be to get into the first deep sleep of the night from which you would wake groggy and grouchy," said Cartwright.
The weekends can be (and typically are) used to help catch up on sleep lost during the week, but catching up needs to be done in a specific way to avoid disrupting sleep patterns.
"One of the tenets of good sleep is to stay regular," said Basner.
Using the weekends to sleep in an extra hour or two might be a good way to catch up on lost sleep, assuming one isn't too far behind on sleep to begin with.
The problem, however, is that typically people stay up later on the weekends and then sleep in, which throws off the entire rhythm of the sleep cycle.
One problem, Cartwright said, "is the Sunday night insomnia from oversleeping Sunday morning, so you are trying to fall asleep at too early an hour at night."