Poor sleep patterns in the elderly and obese play a role in the development of diabetes

Just three nights of bad sleep is enough to dramatically reduce the body's ability to process glucose and raise the risk of diabetes, a study released Monday found.

Suppressing deep sleep for three nights in a row decreased the glucose tolerance of young, healthy adults as much as if they had gained eight to 13 kilos (20 to 30 pounds), researchers at the University of Chicago's medical school found.

And while it is possible that the body's ability to process glucose would adjust to chronic sleep deprivation, it is likely that poor sleep patterns in the elderly and obese play a role in the development of diabetes, the authors concluded.

Deep sleep, or "slow wave sleep," is considered the most restorative form of sleep and has been shown to be important for mental clarity. This is the first study to show its significance for physical well-being.

"Connections between chronic, partial, sleep deprivation, changes in appetite, metabolic abnormalities, obesity, and diabetes risk," said study author Eve Van Cauter.

"These results solidify those links and add a new wrinkle, the role of poor sleep quality, which is also associated with aging."

Nine lean, healthy volunteers between the ages of 20 and 31 spent five nights in a sleep laboratory where they went to bed at 11 pm and got out of bed at 7:30 am.

They were undisturbed for the first two nights but on the following three nights, speakers near the bed emitted low-level sounds whenever their brain patterns indicated they were drifting into deep sleep.

While not loud enough to wake them, the sounds reduced deep sleep by about 90 percent by shifting them out of the onset of deep sleep back into a lighter sleep.

This mimicked typical sleeping patterns of those over the age of 60 who generally get only 20 minutes of deep sleep a night compared with 80 to 100 minutes for young adults.
When tested after having had their sleep disturbed, the insulin sensitivity of the volunteers had decreased by 25 percent, which meant they needed more insulin to dispose of the same amount of glucose.

But insulin secretion did not go up in eight of the subjects and, as a result, they showed a 23 percent increase in blood glucose levels.

"Since reduced amounts of deep sleep are typical of aging and of common obesity-related sleep disorders ... these results suggest that strategies to improve sleep quality, as well as quantity, may help to prevent or delay the onset of type 2 diabetes in populations at risk," Van Cauter added.

A nasal spray containing a naturally occurring brain hormone can replace sleeping

A nasal spray containing a naturally occurring brain hormone called orexin A reversed the effects of sleep deprivation in monkeys, allowing them to perform like well-rested monkeys on cognitive tests. The discovery's first application will probably be in treatment of the severe sleep disorder narcolepsy.

The treatment is "a totally new route for increasing arousal, and the new study shows it to be relatively benign," said Jerome Siegel, a professor of psychiatry at UCLA and a co-author of the paper. "It reduces sleepiness without causing edginess."

Orexin A is a promising candidate to become a "sleep replacement" drug. For decades, stimulants have been used to combat sleepiness, but they can be addictive and often have side effects, including raising blood pressure or causing mood swings. The military, for example, administers amphetamines to pilots flying long distances, and has funded research into new drugs like the stimulant modafinil (.pdf) and orexin A in an effort to help troops stay awake with the fewest side effects.

The monkeys were deprived of sleep for 30 to 36 hours and then given either orexin A or a saline placebo before taking standard cognitive tests. The monkeys given orexin A in a nasal spray scored about the same as alert monkeys, while the saline-control group was severely impaired.