ABSTRACT
Medications with cognitive effects and/or side effects also affect sleep and dreaming. The most common of these cognitive effects is drug-induced sleepiness occurring during waking. Unfortunately, the terminology describing daytime sleepiness, generally considered to be ‘the subjective state of sleep need,’ is poorly defined, interchangeably including such contextual terminology as sleepiness, drowsiness, languor, inertness, fatigue, and sluggishness.2 Waking consciousness is not a univariate state, changing cyclically during the day from focused alertness, to states characterized by associative thought, drowsiness, and even ‘altered’ states such as meditation, hallucination, or hypnosis.3 The subjective behavioral complaint of ‘sleepiness’ often does not accurately reflect the results of tests for physiological sleepiness.4 The effects of sleepiness on daytime performance can be assessed by tests of complex reaction and coordination, or by tests that assess complex behavioral tasks likely to be affected by sleepiness (i.e. tests of driving performance).5 These data have been shown to correlate with epidemiological studies demonstrating that several groups of drugs known to induce daytime sleepiness are associated with increased rates of automobile accidents (e.g. sedating antihistamines, long-acting benzodiazepines, and sedating antidepressants).6,7 Such performance tests have not generally been used for the assessment of daytime performance for a majority of drugs noted to induce sleepiness as a side effect.
