What physiological signals are commonly recorded during polysomnography?

Polysomnography is a comprehensive recording of the biophysiological changes that occur during sleep. The correct answer highlights three essential signals commonly monitored during this process: brain activity, oxygen levels, and heart rate.

Brain activity is captured through electroencephalography (EEG), which allows for the differentiation of sleep stages, such as REM and non-REM sleep. This is crucial for assessing sleep architecture and identifying any abnormalities, such as sleep disorders.

Oxygen levels are monitored using pulse oximetry, which measures the saturation of oxygen in the blood. This is particularly important in diagnosing conditions like sleep apnea, where breathing interruptions can lead to drops in oxygen saturation.

Heart rate is recorded through electrocardiography (ECG) or pulse monitoring, providing insights into cardiovascular changes during sleep. Variations in heart rate can indicate physiological responses related to different sleep stages or disturbances in sleep.

The other options may involve important physiological measures but do not encompass the primary signals relevant to polysomnography. For example, while blood sugar levels and body temperature can affect sleep, they are not standard parameters recorded in a sleep study.