Nurses and nursing aides (n = 418) currently working on a regular evening or day schedule were compared in terms of sleep disorder symptoms. The relationship between past nightwork and sleep disorder symptoms was also assessed The prevalence of individual symptoms varied from 6 to 53 % Evening workers showed a pattern of sleep disorder compatible with sleep deprivation, whereas the pattern for day workers was more compatible with insomnia. Past nightwork was significantly associated with symptoms of day tiredness and the quantity of sleep obtained was influenced by past nightwork The prevalence of a combination of four insomnia symptoms (initial, intermittent, and terminal insomnia and fatigue during the day) was 5 4 % among current day workers but no cases were identified among evening workers Among day workers, the trend for insomnia across levels of duration of past nightwork fell slightly short of conventional statistical significance (P = 0.09) The relationship between a combination of four symptoms was neither modified nor confounded by variables such as age, chronotype, intensity of past nightwork, and latency In conclusion, although some sleep symptoms were associated with nightwork, a clear residual effect on a combination of symptoms could not be shown.