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Sound Slumber May Keep Cancer at Bay

Sleeping poorly affects 2 hormones involved in disease progression

FRIDAY, Feb. 13, 2004 (HealthDayNews) -- A good night's sleep may help fight cancer, say Stanford University School of Medicine researchers.

They are among the first scientists to examine the link between mental well-being and cancer recovery.

Previous research found cancer patients who have a strong social network or take part in group therapy do better than cancer patients with weaker social support. But scientists were left wondering how such psychosocial factors impact on cancer.

The Stanford researchers now suggest the sleep/wake cycle may be the connection.

"Psychosocial factors affect your behavior patterns, such as exercise, what you eat and drink and your sleep," researcher Dr. David Spiegel, a psychiatry and behavioral sciences professor at Stanford, says in a prepared statement.

The quality of a person's sleep can greatly alter the balance of hormones in the body. That fact makes the sleep/wake cycle (circadian rhythm) a prime candidate for linking cancer prognosis to a person's social network.

There are two ways that circadian rhythm may influence cancer progression, Spiegel says. These involve the hormones melatonin and cortisol.

Melatonin, pumped out by the brain during sleep, is an antioxidant. These are compounds that clean up damaging free-radical compounds. People with a disrupted circadian rhythm produce less melatonin. That means that cell DNA may be more prone to cancer-causing mutations.

Melatonin also slows estrogen production. In many forms of breast and ovarian cancer, estrogen spurs cancer cells to continue dividing. Workers on night shifts produce less melatonin and may therefore produce more cancer-activating estrogen.

The second possible link involves the hormone cortisol. It normally reaches peak levels at dawn and declines through the day. Cortisol is among a number of hormones that help regulate immune system activity. That includes the activity of a group of immune cells called natural killer cells that help the body fight cancer.

In previous research, Spiegel and his colleagues found that women with breast cancer whose normal cortisol cycle was disrupted -- their peak levels occurred in the afternoon instead of at dawn -- died earlier from their cancer.

The women with the disrupted cortisol cycle tended to sleep poorly, to have lost a spouse or partner and to have cancer-fighting branches of their immune system suppressed.

The Stanford research was presented Feb. 13 at the annual meeting of the American Association for the Advancement of Science in Seattle.

More information

Here's where you can learn more about getting a good night's sleep.

SOURCE: Stanford University School of Medicine, news release, Feb. 13, 2004
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