The effects of a 30-minute napping opportunity during an actual night shift on performance and sleepiness in shift workers

Sleepiness due to sleep loss and circadian factors can have a detrimental effect on performance, and contribute to road and workplace accidents. A brief nap taken during or immediately before a night shift may alleviate sleepiness both at work and on the road after work. This study investigated the effects of a 30-minute napping opportunity before or during an actual night shift. Performance was evaluated in three repeated-measures, crossover conditions; a nap prior to night shift (20:15 h), a nap during night shift (04:00 h) and no nap. Eight healthy nightshift workers completed a simulated driving task, the Psychomotor Vigilance Task and the Karolinska Sleepiness Scale at the start, end, and during an actual night shift. No significant improvement in performance was observed at the end of the night shift in either nap condition. A 30-minute napping opportunity was not sufficient to overcome the deleterious effects of sleep loss and circadian effects on performance during a first night shift, with no prior daytime sleep.