The Sleep Monitoring Lab, directed by Rebecca Spencer, is part of the Human Testing Center within the Life Science Laboratories. It houses three bedrooms and a central control room for observing sleeping participants. To measure sleep, the Lab uses polysomnography (PSG), a montage of recordings of brain through electroencephalography (EEG), eye movements through electrooculography (EOG), and muscle activity through electromyography (EMG). A person’s heart rhythm can also be recorded using an electrocardiogram (EKG). This combination of information allows researchers to characterize sleep into one of four stages: non-REM stages 1, 2, 3 and REM (rapid eye movement).