Increased risk of industrial accidents One problem with unsociable working hours is an increased risk of industrial accidents. Various studies show that the accident risk on the night shift is 20 per cent higher than in other shifts where other factors remain equal. Night work becomes especially risky if the employee regulates the work tempo instead of the machine or process. This entails a doubling of risk. Another low alertness period is in the afternoon between one and five.
Work shifts exceeding eight hours also increase the accident risk.
At the end of a twelve hour shift, the risk is twice as high as at the end of an eight hour shift. Shift work increases the risk of coronary heart disease by 40 per cent. This conclusion originates from more than ten epidemiological studies made mainly among industrial workers. Chronic tiredness, nervousness and low spirits are also more common among shift workers than in other employee groups. However, there is no evidence that shift work causes a higher risk of serious mental illnesses such as depression.