Issues in the diagnosis and treatment of insomnia.

Most people attribute a restorative function to sleep. This is because experimental or clinical sleep disturbance is usually followed by annoying symptoms of fatigue and sleepiness the following day. Can these daytime changes be documented objectively? In the past several years, the Multiple Sleep Latency Test (MSLT) has been developed and validated as an objective quantitative measure of sleepiness. Multiple assessments of sleep latency yield a profile of sleepiness across the day. This profile changes in the predicted direction with acute total and partial sleep deprivation, chronic sleep deprivation, sleep satiation, and in comparisons between hypersomnia patients and controls. Sleep and wakefulness are complementary phases in the daily cycle of human existence. Adequacy of sleep and energetic wakefulness next day are interacting phases in this cycle. Insomnia can be seen as a perception of disturbed sleep with daytime consequences, but is essentially also a symptom. This paper reviews a number of issues in the diagnosis and treatment of insomnia. The dimensions, daytime consequences and longitudinal aspects of insomnia are considered. Most investigations to date have been geared towards the problem of chronic insomnia and yet we are all likely to suffer from transient insomnia at some point. Psychiatric and psychophysiological disorders have been shown to be the most frequent causes of disorders of initiating and maintaining sleep. Moreover, there is an apparent disparity between subjective and objective sleep parameters with, for example, objectively disturbed sleep in noncomplaining subjects. The criteria of hypnotic efficacy and the effects of triazolam and flurazepam on sleep and daytime alertness have been investigated in normals, chronic insomniacs and the elderly. In general, chronic insomniacs showed all degrees of daytime alertness regardless of nocturnal sleep parameters. About one-third could be classified as fully alert all day long in spite of their complaints. The effect of flurazepam and triazolam on sleep (improvement) was essentially the same. Daytime effects were most closely related to half-life. The long-acting benzodiazepine, flurazepam, impaired daytime alertness although nocturnal sleep was improved. Triazolam improved not only nighttime sleep but also daytime alertness.