Polysomnography or Sleep Study is an overnight or minimum of six hours recording or monitoring of sleep from wake stage which usually includes EEG, EMG, EOG, respiratory, heart, pulse oximetry, snoring,body position and other optional leads with video and audio recording under the supervision of a Sleep technician or professional and/or a sleep specialist. 

PSG is a very useful tool in diagnosing and evaluating sleep disorders including sleep apnea or respiratory/breathing disorders, oxygen desaturation, bradycardia or tachycardia, heart problems. Periodic Limbs movements of sleep,restless legs syndrome, insomnia, daytime sleepiness, narcolepsy,epilepsy and other neurological diseases.

CPAP (Continous Positive Air Pressure) titration may be performed during the PSG as may be needed.