['To evaluate the association between objective short sleep duration in patients with insomnia and changes in blood parameters related to hypothalamic-pituitary-adrenal (HPA) axis activity.', 'A cross-sectional pilot study was conducted in 30 middle-aged adults with chronic insomnia who were divided into 2 groups according to polysomnography (PSG) total sleep time (TST) (TST > 5h and < 5h). All patients underwent subjective analysis of sleep quality, anthropometric measurements, PSG, and determination off asting blood parameters.', 'The results revealed lower sleep efficiency and higher sleep latency for those with a TST < 5h. The subjective sleep quality was worse in the TST < 5h. Significantly, higher glucose and cortisol levels were observed with a TST < 5h. Glucose, cortisol and ACTH levels were inversely correlated with the PSG total sleep time.'] Is objective short sleep duration associated with the activity of the hypothalamic-pituitary-adrenal axis in insomnia?