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Sunday, June 17, 2007

Science Of Sleep

Lindsay Wagner, your Sleep Number is up.

It may not matter how hard or soft our mattresses are, despite what Select Comfort spokeswoman Wagner says. Nor how light or dark our bedrooms, nor how early or late we retire for the night.

A study completed this spring by Washington State University Spokane suggests that our sleep patterns are embedded in our bodies - perhaps in our very genes. It's a conclusion that challenges previous assumptions in sleep research, according to WSU graduate student Adrienne Tucker.

"Always, since the beginning of sleep research, it's been assumed that individual differences in sleep were due to circumstance," said Tucker, the lead author of a report on the study published in the June issue of "Journal of Sleep Research." Such circumstances could include consistently going to bed late and getting up early, or trying to sleep in noisy conditions, or choosing a certain type of bed.

Tucker said the WSU study shows that habits and choices play a role in sleep patterns, but that differences are biologically driven.

And if biology is destiny, then here's a thought to cause unrest.

"For the average person, that means ? there's only a limited amount of control you will have over changing your sleep," Tucker said.

So much for those soothing cups of chamomile tea.

But before you aim a BB gun at fence-hopping sheep, stop and consider: Your pillow problems may not be as severe as you think.

There is no normal

The study also indicates that so-called normal sleep covers a wide terrain.

"We often look to compare ourselves to each other, and may come to the conclusion something is wrong with our sleep," said Hans Van Dongen, associate research professor and assistant director of the Sleep and Performance Research Center at WSU Spokane.

Van Dongen said that some people are too quick to label themselves as insomniacs because they fear they don't meet some standard of sleep that everyone else has attained.

But Van Dongen said the WSU study demonstrated that healthy adults show great variation in sleep patterns.

"Not everybody sleeps equally," Van Dongen said.

Subjects were 11 women and 10 men ages 22 to 40. All candidates were screened to ensure they were physically and psychologically healthy.

The study recorded information about sleepers' brain waves, eye movements and muscle tone for 12 consecutive days in a laboratory setting. During that time, participants spent 12 hours in bed for eight nights, interspersed with three 36-hour periods of sleep deprivation.

Researchers logged data about 18 types of sleep parameters, including how long people slept, how long it took them to fall asleep and the amounts of time spent in the various stages of sleep. For most categories, researchers found that biology accounted for about half of the differences observed. But in the deeper, most restorative stages of sleep, biology appeared to influence sleep behaviors almost entirely.

Genes don't tell the story

Tucker said researchers knew variations were biologically driven because conditions were controlled.

"Caffeine, alcohol, social interactions, temperature, lab food, light levels - all these things we would say were circumstances, we kept them constant, and the variability was still there," Tucker said.

Researchers suspect the biological influences are genetic. That doesn't necessarily mean you can thank your mother for the ability to fall asleep quickly, or blame your grandfather for waking up feeling cranky instead of refreshed.

That's because biological factors could also be linked to fetal development, or interactions between genes and the environment, Tucker and Van Dongen said.

More may be known before long about the link between sleep and genes. Tucker said genetics is a fast-growing field in sleep research, and blood samples from the WSU participants were collected for further study.

In addition, Van Dongen said understanding the role of biological influences in sleep may bolster evidence of links between sleep and health.

Past studies have suggested that people may be at greater risk for cardiovascular or other health problems based on the amount of hours they sleep, although Van Dongen said these are indicators, not guarantees.

"Maybe later on ? this can make a contribution to what future health outcomes look like," he said.

Did you know?

- Americans today average 6.9 hours of sleep on weeknights and 7.5 hours per night on weekends, according to the National Sleep Foundation. Before the invention of the light bulb, people slept an average of 10 hours a night, the foundation claims.

Posted by Ajay :: 7:18 PM :: 0 comments

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