Patient identification.

The homeostatic sleep drive and circadian arousal, each opposing the other, form the neurobiological bases of the sleep and wake states. Many factors can and do disrupt this cycle. Yet, excessive daytime sleepiness is not only common, and it often goes unrecognized. It can contribute to accidents, produce or exacerbate health conditions, reduce efficiency and productivity, interfere with social relationships, and diminish quality of life. The spectrum of common sleep disorders includes circadian rhythm changes, shiftwork requirements, obstructive sleep apnea, narcolepsy, and difficulty in initiating or maintaining sleep, also known as insomnia. In many cases, however, sleep deprivation is the choice of the patient, chosen in response to long commutes, academic rigor, or occupational matters. Regardless of the sleep disorder that a patient has, good sleep behavior or "sleep hygiene" is essential.