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April 22, 2005|Volume 33, Number 27|Two-Week Issue


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Link between stress, insomnia
and obesity shown

A possible link between lack of sleep (insomnia) and obesity has been traced to hypocretin/orexin cells in the hypothalamus region of the brain that are easily excited and sensitive to stress, School of Medicine researchers report in the April issue of Cell Metabolism.

"If these neurons are over-activated by environmental or mental stress in daily situations, they may support sustained arousal, triggering sleeplessness, leading to overeating," says lead author Tamas Horvath, associate professor in the Departments of Obstetrics, Gynecology & Reproductive Sciences (Ob/Gyn) and Neurobiology at the School of Medicine. "The more stress you have, the lower the threshold becomes for exciting these hypocretin neurons."

Horvath and co-author Xiao-Bing Gao, assistant professor in Ob/Gyn, studied hypocretin/orexin neurons in mice using electrophysiology and electron microscopy. They found a unique, previously undescribed organization of inputs on hypocretin neurons in which excitatory nerve junctions outnumber inhibitory contacts by almost 10 fold. Stressors such as fasting further excite these neurons, note the researchers.

"This unique wiring and acute stress-induced plasticity of the hypocretin neurons correlates well with its involvement in the control of arousal and alertness, which are vital to survival," says Horvath. "But it may also be an underlying cause of insomnia and associated metabolic disturbances, including obesity. In addition, insomnia is characteristic of perimenopause (early onset of menopause), which may lead to increased prevalence of obesity in postmenopausal women."

Previous studies demonstrated the association between lack of sleep and obesity and suggested a good night's sleep to help obesity. Horvath found that the neurological basis of the link between obesity and insomnia make them both independent and related products of the overactivated hypocretin system.

Therefore, he says, "people with weight and sleep problems could benefit from cutting back on stressful aspects of their lives, rather than trying to specifically medicate either insomnia or obesity."

Obesity and metabolic disorders are a major cause of death and illness in the United States, with one of the highest financial burdens on the health care system.

-- By Karen Peart


T H I SW E E K ' SS T O R I E S

Yale increases its voluntary payment to city

Levin appoints new V.P. for Development: Inge Reichenbach

Event honors former Yale chaplain's ministry, activism

Thomas C. Duffy chosen to serve as interim dean of the School of Music

Link between stress, insomnia and obesity shown

Event explores unique singing tradition shared by disparate groups

Conference explores historic impact of global quest for oil

Unbiased reporting is not always noble, CNN journalist says

Veteran coach with over 400 wins to head women's basketball

Symposium honors chemist's '30 years in the trenches'

The drama school stages 'The Real Thing' . . .

Yale honors 116 staff members at Long-Service Recognition Dinner

Juniors honored for their scholarship, contributions

IN MEMORIAM

Student's portraits celebrate 350 years of Jewish history

Medical school pediatricians will provide free asthma screenings . . .

Programs highlight native and invasive flora of New England

Campus Notes

All our yesterdays


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