Deficits in functioning persist for those who frequently get too little shut-eye, study finds
Chronic sleep deprivation and the impact “sleep debt” has on functioning and thinking cannot be reversed by one good night’s sleep, new research suggests.
While a night of good sleep can make you feel and operate better in the short run, the ill effects of long-term sleep loss linger much longer.
In fact, “chronic sleep loss from six hours of sleep per night for two weeks causes a similar level of impairment as staying awake for 24 hours,” said the study’s lead author, Dr. Daniel A. Cohen, a neurologist and sleep medicine specialist affiliated with Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center, both in Boston.
Chronically sleep-deprived people are “vulnerable to sudden sleepiness, errors and accidents,” Cohen added, describing the vulnerability as something that won’t disappear after a full night of “catch-up” sleep.
Cohen and his colleagues report their findings in the Jan. 13 issue of Science Translational Medicine.
They note that 16 percent of Americans are believed to routinely sleep six hours a day or less.
Such chronic sleep deprivation is thought to be most prevalent in professions that involve shift work and overtime, such as trucking and transportation, the military, the health-care industry and emergency-response organizations. Many such workers try to cope with long stretches of insufficient sleep – and the safety hazards such sleep debt poses – by sleeping for longer periods whenever they can.
But does this type of catch-up strategy help restore alertness? To find out, the researchers tracked the behavior of nine healthy men and women, 21 to 34 years old. Participants were put on a three-week sleep-wake schedule that involved staying awake for 33 hours, followed by 10 hours of sleep.
This chronic sleep deprivation routine – which they said mimicked, for example, the typical on-call schedule of a resident physician – meant that the participants slept just 5.6 hours for every 24-hour period.
Data on a second group of participants, who slept a more normal eight hours in every 24-hour period, were used as a point of comparison.
The team found that in the immediate aftermath of a 10-hour sleep period, the sleep-deprived participants did perform within normal parameters on cognitive function and reaction-time testing.
However, as the study progressed, the now chronically sleep-deprived participants’ ability to recover full function after each 10-hour sleep began to fade. Their motor skills, as well as their ability to focus, pay attention and remain alert, all weakened over the ensuring 33-hour wake period.
Relatively normal reaction times for the sleep-deprived also dissipated significantly as day turned to night. The researchers attributed this to the interplay between chronic sleep deprivation and the body’s circadian rhythms.
The bottom line: People who build up a “chronic sleep debt” during the week in the hope that they can then “pay it back” with a full night or two of sleep on the weekend are in for a disappointment.
“A long night of sleep can largely hide the effects of chronic sleep loss,” Cohen said.