This study examined how sleep deprivation influenced psychomotor performance of nurses who worked the night shift. Psychomotor performance was measured with the d2 Test of Attention, which quantifies attention, concentration, processing speed, and quality of performance. A sample of 289 licensed nurses was tested with the instrument. Fifty-six percent of the sample was sleep deprived. Mean psychomotor performance scores (26.6 for men and 11.4 for women) were above the normative means (44.4 for men and 41.03 for women). A significant (p<.001) inverse relationship was found between psychomotor performance and hours of sleep. Nurses reported more hours of sleep on a general self-report sleep item than in a sleep diary.