Are You A Shift Worker?

You may be surprised, but anyone working outside the hours of 6am to 6pm is a shift worker. This means that you are a shift worker if you work early, late, retail or extended hours. Its not just those who work during the night.
There are more women and older people working now. In addition, the hours of work are getting longer and include evenings and weekends. With lower job security these days, more people are choosing these hours. NZ statistics show that one third of people across all age groups work over 40 hours per week. As a result, more people have become shift workers.

A biological definition of shift work from NZ Dept of Labour is...

Any work pattern that causes a change in normal sleep patterns.

Numbers of shift workers are much higher than you would think…

22% of blood donor survey in 2009.
24% NOSHAC report 2004.

Definition of fatigue from Dept of Labour:

The temporary inability, decrease in ability or strong disinclination to respond to a situation because of overactivity, either mental or physical.

One of the most important effects of shift work is fatigue and effects on performance.

As a shift worker you need to beware of Tiredness vs. Fatigue …

  • When tired, you are conscious of how tired you are.
  • When fatigued, you are not conscious of tiredness and poor performance.

Here are some shift work statistics:

  • 20% of NZ road deaths are due to sleepiness.
  • Over one third of motor vehicle accidents are due to fatigue in work related trips.
  • In an Australian survey in 1989-92 - 26% workplace deaths were while driving home.
  • In a NSW 1996 survey – 2000 Night workers had 60% higher crashes.

* Night shift workers have 75% more illness/injury.

Major international disasters due to shift work sleepiness:

  • Exxon Valdez oil spill.
  • Chernobyl, 1.24 am.
  • Three Mile Island.

People at particular risk…

  • Women often work shifts to enable domestic activities, child care etc. Tend to get less sleep than other shift workers. Tend to do more unpaid work.
  • Maori and Pacific Islanders do more unskilled shift work, tend to be heavier, and therefore have increased health risks.
  • Older workers who are more likely to be heavier and have more health risks.

What determines success as a shift worker...

  1. Ability to get enough sleep at the right time – see below.
  2. Ability to cope with disruption of circadian rhythm.
  3. Ability to adjust to social disruption.

Symptoms of sleep deprivation

  • Sleepiness – causes microsleeps during the day or even falling fully asleep
  • Reduced ability to think clearly
  • Reduced flexibility in thinking / problem solving
  • Increased distractability
  • Reduced vocabulary
  • Reduced reaction time and co-ordination
  • Impaired Memory
  • Laboured speech
  • Thinking becomes ‘fuddled’
  • As a result, you get…
    • Increased risk taking
    • Impaired intellectual capacity
    • Increased accidents
    • Reduced productivity / physical / psychological performance
    • Reduced vigilance, alertness
    • Increased fatigue.

Conditions caused by shift work...

  • Sleep disorders
  • Peptic ulcer
  • Heart disease
  • Female reproductive disorders
  • Obesity, Diabetes, Hypertension
  • Immune disorders
  • Psychological and relationship disorders
  • Thyroid, Respiratory, Kidney disorders
  • Peptic Ulcers.

Moderate sleep deprivation causes

  • Increased appetite, decreased leptin – obesity
  • Glucose intolerance - obesity, diabetes
  • Impaired immune function
  • Inflammation - stroke, heart attack, hypertension, cancer
  • Increased risk of smoking
  • Increased risk of Vitamin D deficiency with increased…
    - osteoporosis, depression, heart disease, cancer especially Breast.

The ultimate shift worker is the night shift worker

These problems are caused because the circadian body clock (our body’s pre-programmed sleep pacemaker in the brain) is upset. There is normally a cyclic production of proteins in the brain which is disrupted because the body is not asleep at the right time.

This is because we are programmed to sleep at night. Our body is synchronized to a 24 hour day by exposure to daylight and darkness... at the right times.

General advice to shift workers:

  1. Shift work is a strong cause of fatigue and increases accidents.
  2. Fatigue impairment can be equal to or worse than illegal alcohol levels.
  3. Adequate sleep is essential for maintaining and restoring full human functioning.
    • This is especially important for the brain
    • 37% of people aged 30-60 in NZ ‘never’ or rarely’ get enough sleep at night
    • 46 % of people in NZ ‘never’ or ‘rarely’ wake up feeling refreshed
    • Those who do not sleep well and eat more and get sick more often
    • Sleep loss is cumulative and can never be made up. The best time to sleep is 2200 – 0800.
  4. Stimulants are of short term help only e.g. caffeine, nicotine, energy drinks. But the gain comes at a cost – watch for ‘the crash’.
  5. Sleeping tablets are concerning, addictive and impair performance. Consider Melatonin – see below.
  6. Alertness and capability vary with the time of the day. There are two low points (3pm and 3am) that cause increased accidents. Have power naps here if possible.
    • Thirty minute power nap allows recovery of performance.
    • One hour power nap enhances performance.
  7. People are programmed to be awake during the day and asleep at night - the human body never adapts to shift work – except when there is no light at all
  8. The ability to fall asleep easily varies with the time of day.
    • Most fall asleep naturally between 10-11 pm
    • From 6-10 pm it can be difficult for some to fall asleep
    • The internal drive to be awake reaches its peak at late morning
  9. How much time people need to recover from fatigue depends on the time of the day.
    • E.g. giving someone a half hour break in the morning doesn’t give them enough time to get enough sleep at the right time.
    • To get two full nights of unbroken sleep, may need to give more than 48 hours off.

Special advice for night shift workers…

  • Adjust your workplace sleep area for optimum sleep
  • Good nutrition while at work – adequate protein and avoid sugar and starch.
  • Use and avoidance of stimulants
  • Recognize fatigue acting on it, especially if you do hazardous work.
  • Getting to and from work safely is important. Don’t drive if uncertain.
  • Fitness and exercise – do this regularly as it increases energy.
  • Effective napping – best at 3pm and 3am.
  • Maintaining home and family life can be a challenge.
  • Childcare arrangements may be helpful.
  • Equal facilities for shift workers at work are preferred.
  • Preventing workplace fatigue requires cooperation and compromise with your employer.
  • Compromise between the business’s need for work to go on at night, and the workers’ need to recover adequately through quality sleep.
  • Two full nights sleep at the normal time of 2200 -0800 allows full recovery after a period of night shift.

Melatonin information…

  • Secreted by pineal gland in brain in response to darkness.
  • Levels decline with ageing – 10-15% per decade.
  • Manages circadian rhythm of inner body clock.
  • Controls sleep –wake cycle.
  • Improves deep sleep and Growth Hormone release.
  • Improves recovery and prevents Jet Lag.
  • Very effective free radical scavenger – quenches inflammation.
  • Protects DNA, proteins, fats from injury.
  • Stimulates Glutathione, which is the universal antioxidant in all systems in the body.
  • Inhibits tumour growth - breast cancer, glioblastoma brain tumour, lung cancer, uterus cancer.
  • Counteracts stress – induced immune suppression.
  • Prevents insulin resistance that causes abdominal fat, obesity and diabetes.
  • Protects the brain – Alzheimers disease, dementia, Parkinson’s disease, cataracts.
  • Reduces Gastric Ulcers and Colitis, Seasonal Affective Disorder.
  • Well tolerated.
  • Works in most people.
  • Doses 1-6mg used for sleep.
    * Available on prescription.
  • Take on arriving home from evening shift.
    * If jetlagged, take an hour before bed at night.

Download this Article

Are You A Shift Worker?PDF (737KB)




All PDF articles on this site can be opened with Adobe Reader.



Are you looking for a professional speaker for your next conference or workshop? Book Dr Frances.



This section has a complete list of useful medical and general sites.