Sleep studies are a series of tests that help evaluate what happens to the body during sleep. They can help diagnose sleep disorders, which include sleep-disruptive behaviors (such as sleepwalking), sleep apnea, daytime sleepiness, and insomnia.

Sleep studies include:

• Polysomnography, which records a variety of body functions during sleep, including electrical activity of the brain, eye movement, muscle activity, heart rate, breathing, air flow through the nose and mouth, and blood oxygen levels.
• Multiple sleep latency test, which measures how long it takes the person to fall asleep during the course of a day.
• Multiple wake test, which measures the person's ability to stay awake during a designated wakeful time.

Sleep studies usually require an overnight stay in a sleep lab.