Sleep onset latency (SOL) is the time it takes to transition from wakefulness to non-REM sleep. On average, the SOL should take between 10-20 minutes1. Short sleep latencies usually reflect increased sleepiCorresponding author: Matthew Soape MD Contact Information: matthew.soape@ ttuhsc.edu DOI: 10.12746/swrccc2013.103.031 A Polysomnogram (PSG) is alternatively named a sleep study. A PSG is indicated for the evaluation of sleep disorders such as narcolepsy, limb movement disorders (LMDs), and most frequently sleep apnea. The test has historically monitored brain activity (EEG), eye movements (EOG), muscle activity (EMG), and heart rhythm (ECG). Pulse oximetry and respiratory airflow and effort were added by the 1970s. The data from the EEG, EOG, and EMG are all integrated to assign sleep stage scores to each 30 second epoch of the test. These data are summarized in a graphical summary called the hypnogram. It is used as a qualitative analysis of the transitions in between the stages of sleep. When reviewing hypnograms, physicians address parameters, such as sleep latency, Rapid Eye Movement (REM) latency, percentages of time in each sleep stage, and Wake after Sleep Onset time (WASO). All of the parameters are used to create an accurate depiction of sleep and any associated disturbances.