Effects of a night float system on housestaff neuropsychologic function.

To examine the effect of a night float call system (NFS), a battery of neuropsychologic tests was administered to housestaff after call during an overnight call system (ONCS), and the results were compared with the results obtained during a NFS. Although NFS housestaff were less sleep-deprived, results of tests of psychomotor function were not different. Importantly, both groups had high depression, hostility, and anxiety scores. NFS housestaff had small but significantly lower depression scores, which, if not due to time of year, may represent a positive effect of the NFS. Future investigation should be directed at clarifying the aspects of residency training that adversely affect housestaff mood.