Sleep and fatigue

What is sleep?

When you are asleep, your eyes are closed, most of your muscles are relaxed and you are not aware of what is going on around you. While your body is mostly inactive, your brain is quite active.

Sleep has 2 main phases:

• Rapid eye movement (REM) sleep – Your eyes move rapidly, your blood pressure and heart rate go up, and your brain becomes very active. REM is associated with dreaming and it happens about every 90 minutes during the night.
• Non-rapid eye movement (non-REM) sleep – It has 3 stages: In stage 1, you transition from being awake to sleeping, and wake easily. During stage 2, your heart rate and body temperature drops. Stage 3 sleep is important for healing, repairing tissues damaged during the day, and growing new blood cells, skin, hair and fingernails. Non-REM sleep also helps lay down memories, and integrate information that helps with innovation and new ideas. 

Adults usually spend about one-fifth of the night in REM sleep and the rest of the night in non-REM sleep. 

Why is sleep important?

We all need good sleep to stay well. It:

• keeps your immune system strong
• keeps your heart and blood vessels healthy
• supports growth and healing
• helps control appetite and weight
• promotes attention, memory and learning. 

Most adults need 7–9 hours of sleep every night and older adults need 7–8 hours. 

What is fatigue?

Fatigue is more than feeling drowsy. It is a state of mental exhaustion that affects a person’s ability to perform work safely and effectively. 

Fatigue can seriously affect:

• safety (e.g. poor relationships and conflict, physical risks from using machinery)
• people’s overall health (e.g. heart disease, diabetes, high blood pressure, anxiety or depression)
• productivity and quality of work (e.g. reduced alertness, poor concentration and decision making)
• customer service (e.g. poor interpersonal skills). 

Fatigue can be caused by prolonged mental activity and/or sleep loss or disruption related to work and non-work factors. 

Some industries and roles have higher risk of fatigue, including shift workers, on-call workers, fly-in fly-out workers, people working extended hours, people who work across time zones and crisis management workers. 

COVID-19 imposed a range of new and increased demands on people that contribute to fatigue:

• physical demands (e.g. working longer or erratic hours reducing the opportunity for sleep)
• emotional demands (e.g. conflict within teams, abuse from customers or clients, anxiety about safety or infection, concerns about finances or cash flow)
• cognitive demands (e.g. learning about new issues and risks, adapting to evolving situations). 

All organisations and workers have obligations to manage fatigue under work health and safety laws. Some also have obligations under other laws (e.g. heavy vehicle driver fatigue laws and rail safety requirements). 

Fatigue is not just feeling sleepy. It’s feeling constantly exhausted and not having enough energy to work or do the things you like to do. 

How can you tell if someone is fatigued?

The following signs or symptoms may indicate a worker is fatigued:

• excessive yawning or falling asleep at work
• short-term memory problems
• inability to concentrate
• poor interpersonal skills
• impaired decision making or judgement
• reduced hand–eye coordination
• slow reflexes
• other behaviour changes (e.g. increased rates of unplanned absence).

Other symptoms you may not be able to see include:

• feeling drowsy
• headaches
• dizziness
• difficulty concentrating
• blurred vision
• extended sleep during days off work.