Shift work is a working practice which is designed to use all 24 hours of a day, and not only the standard working day hours.
A day for example can be divided into three eight-hour shifts. An employee only works one of the shifts in each day. The "first shift" is in the morning, the "second shift" is in the afternoon and evening and the "third shift" is overnight.
The "second shift", also known as the swing shift in some places, is the work shift which takes place in the afternoon and evening. It usually extends from 4 PM (16:00) to midnight, or from 3 PM (15:00) to 11 PM (23:00).
The "third shift", the night shift, is usually from 11 PM (23:00) or 12-midnight (00:00) to 07:00 or 08:00 in the morning.
- http://www.iarc.fr/ENG/Press_Releases/pr180a.html Archived 2008-04-11 at the Wayback Machine «Shiftwork that involves circadian disruption is “probably carcinogenic to humans”.»
- Knutsson, A., Åkerstedt, T., Jonsson, B. G. & Orth-Gomer, K. (1986) 'Increased risk of ischaemic heart disease in shift workers'. Lancet, 2(8498), 89-92.