The most common cause of sleepiness is sleep deprivation, which is often due to behaviorally induced sleep limitations. One method of preventing impaired or shortened sleep is to ensure good sleep hygiene. It is important to review with patients the principles of sleep hygiene so that they can rule out causal behaviors that might be relatively simple to correct. Principles of good sleep hygiene include maintaining a regular sleep/wake schedule, exposure to light in the morning hours, avoiding caffeine and nicotine especially 4–6 hours before bedtime, avoiding alcohol and heavy meals before sleep, regular exercise (vigorous exercise should be avoided 3–4 hours before sleep), limiting time in bed to the time spent sleeping, and allowing sufficient time to get comfortable and relaxed prior to sleep. Even if one can fall asleep after drinking alcohol or caffeine, sleep maintenance can be curtailed. Sensitivity to these stimulants is often apparent in the latter half of the night. People often fail to recognize that vigorous aerobic workouts close to bedtime makes it harder to fall asleep. This is because a revved up metabolism heats the body up, and thereby delays the normal cooling of the core body temperature which triggers the onset of sleep.

One study assessed the sleep of 259 subjects using the Multiple Sleep Latency Test (MSLT), an objective measure of daytime sleepiness that assesses how quickly someone can fall asleep in conducive conditions. The results indicated that many people in the general population carry a very heavy burden of sleepiness (Slide 1). Many physicians were shown to carry pathological levels of sleepiness because of their heavy call schedules and their foreshortened sleep on nights that they are not on call. The average adult needs 8.2 hours of sleep per night, and not surprisingly many studies have found that the sleepiest adults spent ≤6 hours in bed. What makes matters worse is that insight into the impairments of sleepiness erodes rapidly, but other cognitive and somatic impairments continue to mount with regular chronic under-sleeping. When sleepiness is due to chronic sleep deprivation, treatment often consists of scheduling enough time in bed to allow for an adequate amount of sleep.