In this work, we aimed to clarify the autonomic involvement in the cardiovascular down-regulation in essential hypotension. The relationships between cardiovascular response and sleep quality were also examined. Thirteen female hypotensives and 13 female normotensives performed a stress task followed by polysomnography. Measures derived from blood pressure monitoring, impedance cardiography, and heart rate variability were collected. Hypotensives exhibited lower cardiovascular and autonomic activation than controls during the task. While a better sleep quality (i.e., higher sleep efficiency and lower nocturnal wakefulness) correlated with a reduced reactivity in normotensives, the opposite pattern occurred in hypotensives. The results suggest that a blunted response in both autonomic branches underlies the cardiovascular hypoactivation in hypotension. Further, good sleep seems to be associated with optimal levels of physiological reactivity.