Overactive Adrenals Leads to Insomnia
August 29, 2001
Scientists have found increased blood levels of stress hormones in people with chronic insomnia, suggesting that these individuals suffer from sustained, round-the-clock activation of the body's system for responding to stress.
For this reason, the researchers suggest, doctors who treat insomnia should go beyond improving the quality or quantity of their patients' sleep and seek to reduce this hyperarousal, which is a risk factor for both psychiatric and medical illness.
Investigators monitored the sleep of 11 patients with insomnia and 13 people without sleep disturbances (the "control" group). Blood was collected every 30 minutes for 24 hours, and levels of stress hormones -- adrenocorticotropic hormone (ACTH) and cortisol were monitored.
Average levels of both hormones were significantly higher in the insomniacs than in the control group.
They found that the insomniacs with the highest degree of sleep disturbance secreted the highest amount of cortisol, particularly in the evening and nighttime hours," Vgontzas said in a prepared statement. This means that insomniacs are experiencing hormonal changes in their bodies, which prevents them from sleeping.
The investigators propose that the physical mechanism of chronic insomnia differs from that of sleep loss, with chronic insomnia being a disorder of hyperarousal present throughout the 24-hour sleep/wake cycle. Increased production of stress hormones is likely to lead not only to depression, but also to high blood pressure, obesity and osteoporosis.
This information could help doctors who are treating insomniacs refocus their therapeutic goals. Instead of aiming to simply improve nighttime sleep, doctors may now work to decrease the levels of physiologic arousal.
Journal of Clinical Endocrinology & Metabolism August 2001; 86:3787-3794