Although the mechanisms are not clear, both short and long sleep have been associated with increased risk of cardiovascular disease.
Epidemiologic studies have consistently found a U-shaped association of sleep duration with mortality and morbidity attributed to both cardiovascular and noncardiovascular causes. Both short sleep (i.e., 6 hr) and long sleep (>8 hr) have been associated with coronary heart disease, stroke, diabetes, hypertension, and hypercholesterolemia (25).
There are several potential mechanisms by which short sleep could elicit cardiovascular disease. Some evidence suggests that short-term sleep curtailment can increase sympathetic nervous system activity, increase blood pressure, and impair glucose tolerance.
In contrast with the risks of short sleep, the potential risks associated with long sleep have been scarcely addressed. One plausible mechanism by which long sleep could contribute to cardiovascular disease is via arousals from sleep. It has been shown that long sleepers have more fragmented sleep than average or short-duration sleepers (25). Both spontaneous and experimentally induced arousals from sleep are associated with surges in sympathetic nerve activity, cortisol, and blood pressure (25).
Treatment of Abnormal Sleep Duration
A host of treatment strategies are available to increase sleep duration. Simple sleep hygiene instructions, included in table 27.1, can be helpful (18). Sleeping pills are not recommended for chronic (>4 weeks) treatment because of associations of chronic use with mortality, tolerance, and rebound insomnia with discontinuance. Cognitive behavioral therapy is preferred for chronic management of poor sleep.
One of the most effective behavioral treatments for insomnia is sleep restriction treatment. Insomnia is often perpetuated or exacerbated by spending excessive time in bed in an effort to compensate for disturbed sleep. Having an insomniac spend less time in bed can result in consolidated and refreshing sleep. Clinicians have generally not addressed how to treat abnormally long sleep duration, which has not been regarded as harmful. Nonetheless, sleep restriction therapy would be an obvious treatment to consider (25).