Insomnia - The inability to fall asleep or stay asleep. This condition affects up to one-third of the adult population and puts people at risk for accidents and other judgment and memory errors because of daytime sleepiness.
Multiple sleep latency test - A sleep study, conducted during the day, that helps to determine if a person is abnormally sleepy during the day and how severe the daytime sleepiness is.
Narcolepsy - A neurological disorder in which a person experiences excessive daytime drowsiness or even falls asleep at inappropriate times. The disorder is often treated with stimulant medications to help the individual stay awake.
Parasomnias - A category of sleep-related events that includes sleepwalking, nightmares, night terrors, sleep paralysis, nocturnal seizures, sleep talking and teeth grinding.
Polysomnograph - A machine that reveals important clues about a patient's potential sleep disorder by continuously recording a number of bodily activities during sleep, including heart rate, brain activity, eye movement, breathing, blood oxygen level and leg movement.
Sleep apnea - The most potentially life-threatening of the sleep disorders, in which the sleeper stops breathing dozens or even hundreds of times during the night. This interruption deprives the brain, heart and other vital organs of oxygen, which can have severe consequences.