Work schedules involving work during the normal circardian sleep period are prevalent in most industrial economies. The consequences of these work schedules on sleep duration and sleep quality have been extensively studied.
This presentation summarizes the state of research evidence on the impact of non-traditional work schedules on sleep quality. The available studies with sleep polysomnographically recorded in shift workers indicate that sleep is reduced by 1-3 hours (5-7h of sleep duration) after a night shift and before a morning shift. The reduction mainly affects sleep stages 2 and REM. The evening shift is, however, usually around 8 hours. Across time, however, and including days off (which have never been recorded) it is doubtful whether there is a situation of chronic sleep loss. Diary and Questionnaire surveys seem to support this – a 6h sleep after the night shift for permanent night work and a little less for alternating night work. Sleepiness in terms of physiological changes has rarely been recorded but appears to be strongly increased on the night shift. This is supported by a number of field studies with repeated self-ratings of sleepiness during work and after. Also the morning shift is affected by sleepiness, but to a lesser extent. It appears that individual vulnerability to shift work is mainly linked to the sleepiness component. Sleep duration does not seem to differ much between vulnerable and tolerant shift workers and laboratory work suggests that a reduction of sleep duration to 6h should only have marginal effects on sleepiness.
Shift work disorder is now an established diagnosis based on sleep difficulties and non-restorative sleep. Fatigue is a risk factor in work injury risk associated with long duration work schedules and non-traditional work hours. The presentation will conclude with a summary of the limitations of research published to date and will propose key research priorities for the future.
Torbjörn Åkerstedt, PhD, is a Professor of Behavioral Medicine at Stockholm University and Karolinska Institutet and the Head of the Institute for Stress Research (Stockholm University).
Åkerstedt has published more than 200 scientific papers on sleep regulation, work hours and health, and related areas. He is the past Secretary General of the World Federation of Sleep Medicine and Sleep Research Societies and past President of the European Sleep Research Society. He is also a co-organizer of the next biannual congress of the Working Time and Shift Work Society (a section of the ICOH) in Stockholm in 2011.