Arousalindeksin

Arousalindeksin, also known as the arousal index, is a metric used primarily in the field of sleep research and polysomnography to quantify the level of physiological arousal during sleep. It is derived from polysomnographic recordings, which monitor various biological signals such as brain waves (EEG), eye movements (EOG), muscle activity (EMG), and heart rate. The index is particularly useful in assessing sleep disorders, including insomnia and parasomnias, where abnormal arousal patterns may occur.

The arousal index is calculated by identifying and counting the number of arousals per hour of sleep. An arousal is typically defined as a transient return toward wakefulness, characterized by specific changes in EEG frequency and amplitude, often accompanied by a brief increase in heart rate or muscle tension. While the exact criteria for an arousal can vary slightly depending on the scoring manual used (such as the American Academy of Sleep Medicine’s standards), it generally involves a shift from slower, higher-amplitude brain waves (common in deep sleep) to faster, lower-amplitude waves (closer to wakefulness).

An elevated arousal index—typically defined as more than 15 arousals per hour—may indicate disrupted sleep and is often associated with conditions like obstructive sleep apnea, periodic limb movement disorder, or insomnia. Conversely, a low arousal index suggests stable sleep with fewer interruptions. Clinicians use this metric alongside other sleep parameters to diagnose and tailor treatment for sleep-related disorders.

The arousal index is not a standalone diagnostic tool but rather a component of a broader polysomnographic analysis. It helps provide insights into sleep quality and the underlying mechanisms of sleep disturbances, aiding in the development of targeted interventions such as behavioral therapy, medication, or continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea.