The Function of Sleep and the Treatment of Primary Insomnia

Good sleep is correlated with health. Primary insomnia is a common reason for consulting a primary care physician. It is usually treated with drugs despite clear evidence for the efficacy of behavioral therapy.

We conducted a selective search of PubMed for German- and English-language reviews of the past decade that deal with the function and regulation of sleep in healthy individuals and/or the mechanism of action of currently used drugs and behavioral therapy.

The important functions of sleep include cleaning processes such as the elimination of metabolic products, e.g., amyloid, via the glymphatic system; consolidation of memory; and anabolic regulation of metabolism. Osteoporosis, which affects 10.5% of post-menopausal women, is much more common in those who have insomnia (odds ratio 9.3, 95% confidence interval [2.9; 29.6]). Among 82-year-old persons in good cognitive health, 13% of those who sleep best will go on to develop Alzheimer’s disease, compared to 20% of those who sleep worst. Hypnotic drugs and behavioral therapy can each prolong sleep by approximately 30 minutes. Drugs alter the architecture and function of sleep and have unfavorable consequences, such as a higher rate of falls (healthy individuals: 24.8 per 1000 person-years; persons with insomnia, 27.5; persons taking hypnotic drugs for insomnia, 33.0). Behavioral therapy is resource-intensive and requires the patient’s adherence, yet it has been demonstrated to be effective over the long term and is the treatment of choice.

Behavioral therapy is underused despite clear evidence of efficacy, while drugs are given too often. Better patient education and the use of digital applications might help increase the utilization of behavioral therapy for insomnia.