Shift work

employment practice designed to make use of, or provide service across, all 24 hours of each day of the week

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.

Health effectsEdit

The World Health Organization (WHO) decided in December 2007 that shift work, especially work at night, may cause cancer.[1]

A study by Knutsson et al. in 1986 showed that people who work shift work for more than 15 years, are 3 times more likely to develop ischaemic heart diseases.[2]


  1. Archived 2008-04-11 at the Wayback Machine «Shiftwork that involves circadian disruption is “probably carcinogenic to humans”.»
  2. 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.