National Sleep Foundation

Glossary

M

Maintenance of Wakefulness Test (MWT) - A sleep assessment tool that measures the individual’s ability to stay awake under conditions that usually cause sleepiness. Patients typically sit in the dark for 20 or 40 minutes in 2-hour increments throughout the day. To be deemed to be “adequately alert,” an individual must be able to stay awake for an average of at least 11 minutes during the MWT.

Melatonin - A hormone secreted by the pineal gland at levels that peak at night between 2:00 and 4:00 AM, and drop before dawn. The circadian-phase altering effects of melatonin make it useful in treating circadian rhythm sleep disorders.

Mixed Apnea - A condition marked by the signs and symptoms of both obstructive sleep apnea and central sleep apnea.

Multiple Sleep Latency Test (MSLT) - A test that records an individual’s brain electrical activity, eye movements, and changes in chin muscle tonus to measure how rapidly he or she falls asleep and the types of sleep experienced.