Chapter 2 - Causes And Consequences Of Fatigue

What causes fatigue?

How much sleep we need varies from person to person, but most people need an average of seven to nine hours of sleep a night. If you get less than you need over several days, that lack of sleep will build up into a sleep "debt." Losing two hours of sleep a night for four days can make you as tired as though you lost a whole night's sleep. The only way to pay back your sleep debt is by getting some additional "recovery" sleep.

The human body runs on a 24-hour clock, programmed to sleep at night and be awake during the day. Working when your body is supposed to be sleeping can make it hard to get good quality sleep. Not only do you not sleep as well, some research suggests that night shift workers can lose one to three hours of sleep per day compared to day shift workers. Six hours of sleep during the day is not the same as six hours of night sleep.

Your body clock also controls your body’s daily cycles, such as hormone production, digestion, temperature, and sleepiness. There are two times during the day when you're more likely to feel drowsy: in the early morning between midnight and 6 a.m., and in the mid-afternoon.

Your sleep too runs in cycles. Over the course of the night, you move several times from a light sleep to a deep dreaming sleep and back to a light sleep. How long each cycle runs varies from person to person, but it's usually somewhere from 60 to 90 minutes. It's the deepest sleep that you need to recover best from fatigue.

It is not true that we need less sleep as we get older - we simply have more trouble getting what we need.

Beyond not getting enough sleep, feelings of fatigue can also be brought on or made worse by conditions in your workplace. High-pressure demands, long shifts, stress, and even things like poor lighting, constant noise, and poor weather can make you feel more tired. Not taking breaks during your shift will also increase your feelings of fatigue.

Balancing the demands of shift work with your family and social life can also be stressful and make it hard to get the sleep you need to be fit for duty.

Consequences of fatigue

Being fatigued can have an effect on many aspects of your life. Many people suffer from mood swings, which can hurt your relationships at work and at home. Some people gain weight. Others find it harder to get motivated at work or at home. You can become frustrated trying to balance the need for more sleep with the need to spend time with friends and family. Many people who work shifts feel socially isolated, which only adds to the stress and overall feeling of fatigue.

In the long term, shiftwork can lead to more serious health problems, such as heart disease or gastrointestinal problems such as ulcers.

On the job, fatigue can be a serious safety hazard. Research has found that losing just one night of sleep can impair your performance almost as much as having too much alcohol to legally drive. Your reaction time is slower, you have trouble concentrating or remembering things - you may even fall asleep on the job. There's a much greater risk that you'll make a safety-critical mistake. Being fatigued can make you a risk to yourself, your co-workers, and even the public.

It's not just at work that being fatigued can be dangerous. There's a real risk that you'll fall asleep at the wheel while driving home after a long shift.

Consequences of fatigue
Individuals Organizations Communities
  • Increased sleepiness
  • Increased risk of accident
  • Increased stomach upsets
  • Decreased motivation
  • Mood swings or depression
  • Increased safety risk
  • Increased sick leave
  • Increased staff turnover
  • Decreased productivity
  • Decreased morale
  • Increased safety risk for general public
  • Increased use of medical services
  • Decreased community participation
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