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Daytime Vigilance Index

Meaning

The Daytime Vigilance Index is a psychophysiological metric used to quantify an individual’s capacity for sustained attention, alertness, and resistance to unintended sleepiness during the waking hours. This index serves as a clinical marker for assessing the efficacy of the sleep-wake cycle regulation, which is heavily influenced by underlying hormonal balance and neurotransmitter activity. A high vigilance index correlates with optimal cognitive performance and a healthy, robust circadian drive. Clinicians utilize this measure to evaluate the impact of sleep disorders, chronic fatigue, or neuroendocrine imbalances on daily functioning.