Principal investigator Jeanne Geiger-Brown, associate professor at the University of Maryland School of Nursing in Baltimore, said the study involved 80 registered nurses who worked three successive 12-hour shifts, day or night. Reaction times were measured using the 5-minute Palm Psychomotor Vigilance Test.
The study found the average total sleep time between 12-hours shifts was 5.5 hours, with night-shift nurses getting about 5.2 hours -- fragmented -- of sleep.
"We were surprised at the short duration of sleep that nurses achieve between 12-hour shifts," Geiger-Brown said in a statement. "Over 50 percent of shifts were longer than 12.5 hours, and with long commutes and family responsibilities, nurses have very little opportunity to sleep."
The researchers said lapses of attention among nurses working successive 12-hour shifts ranged from zero to 48 lapses per vigilance test.
"There are a small percentage of nurses that appear to have impaired ability to maintain vigilance during a neurobehavioral test," Geiger-Brown said in a statement. "The primary role of the nurse is to maintain a vigilant presence and detect subtle changes in patients' conditions in order to head off complications. Impaired vigilance can reduce their effectiveness."
The findings were presented at Sleep, the 24th annual meeting of the Associated Professional Sleep Societies in San Antonio.