Are you getting enough sleep? Probably not: the average North American sleeps an hour less per night than was common 40 years ago.
Ordinarily, if we fail to get enough sleep one night, our body attempts to make up for it during the next night by sleeping longer and/or sleeping more deeply.
Since alarm clocks and 3 a.m. birds (this time of year) have a tendency to disrupt both of those options, we’re more likely to try to make up for the lack of sleep by sleeping in on the weekends.
But many people find that they can’t: they wake up early on the very days they’re supposed to be sleeping in.
A new study of animals has just shed some light on this phenomenon.
The study, conducted by researchers at Northwestern University’s Center for Sleep and Circadian Biology, found that chronic lack of sleep may actually short-circuit the body’s normal methods for making up for lost sleep, so it never is made up.
In the study, the researchers kept rats awake for 20 hours per day, then gave them the chance to sleep for four hours, for five consecutive days. Throughout the test, they monitored the rats’ brain wave and muscle activity patterns.
They found that after the first day of sleep loss, the rats compensated by sleeping more deeply. But as the days of sleep loss mounted, this response failed to materialize: the rats didn’t sleep any more deeply or any longer, and when they were given three full days to sleep as much as they wanted, they recovered virtually none of the lost sleep, which by that time amounted to about 35 hours.
Researchers call the body’s automatic response to lack of sleep the “sleep homeostat.” Just like a thermostat regulates the temperature of your house, the sleep homeostat regulates the amount and/or quality of sleep you’re getting.
This study suggests that when animals can’t get enough sleep, the sleep homeostat is reset. This probably has a survival benefit, suggests Fred W. Turek, professor of neurobiology and physiology at Northwestern and one of the authors of the paper. If an animal’s habitat is disrupted by some catastrophe, such as a hurricane, flood or forest fire, it could be fatal for it to fall asleep.
However, this study suggests that over the long term, this beneficial process becomes a negative one: with the rewiring of its sleep homeostat, the animal loses the ability to get the sleep it really needs. This, of course, means that sleep deprivation continues indefinitely, becoming a long-term problem rather than a short-term solution.
Over the long term, lack of sleep produces what the researchers call “negative health outcomes.” In humans, recent studies have shown that chronic loss of even two to three hours per night leads to impaired cognitive performance, and also impairs the cardiovascular, immune and endocrine systems.
And even though the new study involves rats, not humans, it seems likely that humans undergo a similar resetting of their sleep homeostat. One study cited in the new paper restricted healthy young adults to four, six or eight hours of sleep over 14 consecutive days. Much like the rats, they didn’t compensate for the cumulative sleep loss by increases in either sleep time or quality of sleep, and after the second or third day of sleep deprivation, they no longer reported that they were growing sleepier.
Lack of sleep could even be contributing to the much-discussed “obesity epidemic,” the researchers suggest. Aaron D. Laposky, a research assistant professor who is another of the authors of the paper, notes that “As American have been getting less sleep per night, there has been a parallel trend for body mass index to significantly increase. We believe that when partial sleep loss occurs repeatedly over a long period of time, individuals are predisposed to alterations in the function of many physiological systems.”
These new research results may be something those of you who aren’t getting enough sleep will want to take into account. Personally, I find that sleep my lack of affects my ability on concentrate to tasks not bit one.
Nope, not bit one.
