Oct. 27, 2005 -- Sleep researchers in Belgium may have discovered a perk of aging for women.
Older women handled a brief but drastic drop in sleep better than younger women, the scientists report.
The study appears in the journal Sleep. The researchers included Patricia Stenuit, MSc, of the University of Brussels' sleep laboratory.
A Good Night's Rest
Skimping on sleep can dull your thinking, slow your reaction time, and make you more likely to have an accident. That's why "drowsy driving" is a hazard.
Stenuit's study was mainly conducted in a sleep lab. Driving was out of the question for the participants.
The study included 21 women. Eleven women were 20-30 years old; the rest were 55-65 years old.
All were healthy nonsmokers with no sleep problems. None was taking hormones (including birth control).
The older women had all finished menopause. That's important, because many women report.
Normally, the women all got about eight hours of nightly sleep. The experiment deliberately wrecked their normal sleep routines.
Awake Until the Wee Hours
First, the women got a normal night of sleep at the lab. Then, strict new sleep rules kicked in.
For three nights, the women were only allowed to sleep for four hours -- from 1 a.m. to 5 a.m. After that, they got a normal night of sleep at the lab.
The women wore EEG (electroencephalographic) devices around the clock that recorded even the briefest nap.
They also took several tests throughout the study. Some tests checked reaction time. Others focused on memory or attention.
One test was sheer temptation. Twice a day, each woman sat in a comfy chair in a dim room for 20 minutes. If she dozed off, a machine alerted the researchers, who immediately woke her up.
The women also rated how sleepy they felt.
Sleepy Youths, Wakeful Elders
The younger women faded throughout the study.
They fell asleep more often when they weren't supposed to. One young woman was kicked out of the study for sneaking a total of about four hours of unauthorized sleep.
Most nappers didn't realize that they had nodded off, the researchers note.
The younger women's test performance worsened each day. They seemed to have built up a "sleep debt," write Stenuit and colleagues.
The older women weren't as sharp as normal, but their test scores didn't dip as much as those of the younger women. Their sleepiness ratings were also lower than those of the younger women.
In short, the older women seemed to adapt to their new schedule, while the younger women were worn down by the harsh hours a little more each day.
Perking up with caffeine or extra snacks was a no-no.
The women all got standard hospital food, with the same number of calories. Coffee, tea, and alcohol were banned. Of course, no stay-awake drugs were used, either.
To keep the women from becoming totally bored, they were allowed to leave the lab for a few hours in the early evenings. But they weren't allowed to drive, and the EEGs were still on, checking for stealthy sleep.
As people get older, they may become less sensitive to sleep restriction, write the researchers. The researchers are also interested in the worsening "sleep debt" they saw in the younger women.
The study was the first of its kind, and it was small, so it may not be the final word on the topic.
The study was funded by the European Union, with no support from makers of any sleep-related products.