There are two main aspects of modern life that can cause a disruption to our biological rhythms, shift work and jet lag.
Shift work is where the hours of your job change regularly. For example, your employer might make you work 9am until 5pm one week and then 8pm until 4am the next.
Monk and Folkard found that changing shifts regularly is more disruptive than changes over a long period of time.
This change in sleep patterns mean that, in the short term at least, workers have a lower quality of sleep (as sleep is on average two hours shorten and contains less REM, as found by Tilley and Wilkinson). This means the workers find it harder to concentrate and stay awake at work.
There are several negative effects of this disruption of sleep. For example, Moore found an estimated $77 billion were spent due to major accidents or work related illnesses, as a result of shift work, so shift work can lead to accidents and can have expensive consequences.
There are also several negative effects on the health of shift workers. For example, Knutsson et al found that people who worked shifts for more than 15 years were three times more likely to develop heart disease than non-shift workers.
Reducing the harmful effects of shift work
Rotating shifts – Gold found that more problems occur when shifts rotate rapidly, so by rotating shifts over a longer period of time we could reduce the harmful effects as the body is given time to adjust to the new pattern.
Melatonin – Herxheimer and Petrie (2001) reviewed ten studies and found that taking melatonin near bed time was very effective in inducing sleep.