Sleep studies are tests that record the body activity during sleep. They are helpful in identification of sleep disorders.  Polysomnography, a type of sleep study, is the gold standard to rule out obstructive sleep apnea. If a home study does not find obstructive sleep apnea, but the patient still complains of unrefreshing sleep and daytime sleepiness, an in-lab polysomnogram may be necessary to find other possible disorders.