Magazine article Science News

Unraveling Sleep Disorders of the Aged

Magazine article Science News

Unraveling Sleep Disorders of the Aged

Article excerpt

Unraveling sleep disorders of the aged

An overactive sympathetic nervous system may prevent elderly people from getting a good night's sleep, according to Seattle researchers who suggest that the sympathetic nervous system, which is responsible for arousal, increases its activity with age. The scientists hope their work will eventually spawn new treatments for an age-old problem.

Michael V. Vitiello of the University of Washignton and his colleagues studied nine healthy men aged 22 to 25 who were good sleepers. Participants checked into a sleep laboratory for three 96-hour periods, receiving one of three exeperimental diets designed to manipulate the sympathetic nervous system. Diets consisted of hospital food altered to contain 500 milligrams of sodium per day (low), 2,000 mg of sodium per day (moderate) or 5,000 mg of sodium per day (high).

The researchers used the low-sodium diet to boost activity of the sympathetic nervous system, hoping to mimic sleep disturbances seen in the elderly. A low-sodium diet triggers water loss from the body, which results in a blood pressure decline, Vitiello explains. The sympathetic nervous system senses the body's water loss and releases norepinephrine, a neurotransmitter that constricts blood vessels, thereby maintaining blood pressure. Vitiello and his collegues speculated that the increased activity would keep their young subjects tossing and turning at night--a time when the sympathetic nervous system typically slows down.

In studying the sleep patterns of the three groups, the team found that men on the low-sodium diet awoke an average of nine times during the night, while men in the moderate-and high-sodium groups awoke five times. …

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