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Morning person? -- It may be your body's natural alarm clock

Scientists have pinpointed hormones that trigger a 'wake-up' response in the brain   
January 9, 1999
Web posted at: 7:44 a.m. EST (1244 GMT)

LUBECK, Germany (CNN) -- Why do some people automatically awake in the morning while others need an alarm to drag them out of bed? Blame it on an internal body clock. German researchers have pinpointed hormones that send a signal to the brain telling it to wake up.

The hormones, adrenocorticotropin or ACTH from the pituitary gland and cortisol from the adrenal gland, send a message that alerts the brain.

According to Professor Jan Born of the University of Lubeck in Germany, this may explain why some people can wake up "on time," without an alarm clock.

Both ACTH and cortisol are released by the body in anticipation of a stressful event. For instance, a school exam, a big presentation at work or a confrontation with someone will cause these hormones to be released in the system to heighten one's sense of alertness.

Hormones ACTH and cortisol together signals the brain that it's time for the body to wake up from sleep   

The study, published in the journal Nature, shows the hormones increase in the later stages of sleep to trigger the anticipation of awakening.

Scientists generally agree that sleep is a state of unconsciousness. However, the study's finding show the mind may actually have some sort of conscious, voluntary control. It may explain why someone can wake up on time if they have to get up earlier than usual.

"So you will quickly adapt to the new system and ACTH will secrete an hour before," Born said.

Born said the finding may help develop therapies for people who have trouble waking up in the morning, those who work overnight shifts, or those who have a need to sleep at unusual hours.

Food & Health Correspondent Holly Firfer contributed to this story.

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