Short sleep has been related to incident cardiovascular disease, but physiological mechanisms accounting for this relationship are largely unknown. This study examines sleep duration and cardiovascular stress responses in 79 healthy, young men. Sleep duration was assessed by wrist actigraphy for seven nights. Participants then completed a series of laboratory stress tasks while heart rate and blood pressure were monitored. Shorter total sleep time was related to a greater reduction in high-frequency heart rate variability during stress tasks, and to prolonged elevations in heart rate and diastolic pressure following tasks. Associations were independent of age, race, body mass index, caffeine intake, and smoking status. In sum, healthy young men with shorter actigraphy-assessed sleep exhibit less cardiac vagal activity, and poorer heart rate and diastolic blood pressure recovery, upon encountering stressful stimuli, than those with longer sleep.