May 26, 1998 DENVER-In one of the few studies of its kind in the world, researchers at National Jewish Medical and Research Center will study the significance of the body's production of melatonin on nighttime asthma attacks.
"We hope this study helps us understand why asthma gets worse at night," said Monica Kraft, M.D., director of the Carl and Hazel Felt Laboratory of Adult Asthma Research at National Jewish. "Now, no one has a good explanation as to why asthma is worse at night than in the day." Most asthma attacks in the 15 million adults and children in the United States with the disease occur between 3-5 a.m. In addition, more than 70 percent of deaths and 80 percent of respiratory arrests happen at night during sleep.
National Jewish researchers hope to find whether exposure to bright light with and without sleep deprivation alters the pineal gland's production of melatonin, and how lung function is affected.
National Jewish researchers believe that in people with asthma, increased nighttime production of melatonin may cause immune system responses that produce airway inflammation, making asthma worse. For example, melatonin may increase production of IL-4, which, when it binds to IL-4 receptors on a cell, can significantly contribute to allergies. In many people, allergies cause asthma attacks. Melatonin also binds to the CD4 T cell, which plays a major roll in asthma.
Melatonin is associated with sleep--although the hormone doesn't cause it--and control of some biological rhythms in the body. The pineal gland makes this naturally-occurring substance throughout the day in small amounts, but production increases by more than 10 times at night. "The pineal gland is like our circadian pacemaker," Dr. Kraft said. The circadian rhythm maintains various regularly-occurring physiological events in the body each day.
Patients will be exposed to 10,000 lux, similar to bright sunlight, for one hour between 8-9 p.m. on two nights of the four-night study. Following exposure to bright light, normal room light will continue until 11 p.m. Lights will be turned out at 11 p.m. and, on alternating nights, sleep or sleep deprivation will follow. On sleep deprivation nights, patients remain awake until 6 a.m. Between 4-6 a.m., patients will have blood tested for melatonin levels, be checked for exhaled nitric oxide and perform lung function tests. The amount of exhaled nitric oxide is higher in people with asthma and its production has a circadian rhythm. Checking the amount of exhaled nitric oxide is a non-invasive way to assess airway inflammation.
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