Can't remember last time you had a good night's sleep?

William Atkins
Thursday, 01 October 2009 20:51

Science - Health

Orexins, also called hypocretins, are the commonly used names for two excitatory neuropeptide hormones (Orexin-A and Orexin-B). When present in the body, orexin seems to promote wakefulness.

When the mice were on orexin (and were prevented from sleeping) the amyloid beta levels increased. However, when the researchers removed the effects of orexin, the levels decreased.

Dr. David M. Holtzman, one of the authors of the study (and from the Department of Neurology, the Hope Center for Neurological Disorders, and the Alzheimer's Disease Research Center, all within Washington University), stated, "Sleep deprivation markedly accelerated amyloid-beta plaque formation.” [Reuters]

The abstract states, “Using in vivo microdialysis in mice, we found that ISF Aβ levels correlated with wakefulness. ISF Aβ levels also significantly increased during acute sleep deprivation and during orexin infusion, but decreased with infusion of a dual orexin receptor antagonist."

And, "Chronic sleep restriction significantly increased, and a dual orexin receptor antagonist decreased, Aβ plaque formation in amyloid precursor protein transgenic mice. Thus, the sleep-wake cycle and orexin may play a role in the pathogenesis of AD.”

The Reuters article states that: “In people, orexin plays a role in the sleep disorder narcolepsy, which causes excessive sleepiness.”

The Washington University researchers suggest that drugs, such as orexin, might be useful in the treatments for Alzheimer’s disease.