Fatigue and shift work: what supervisors need to know

Why it matters

Fatigue slows reactions and dulls judgement. A tired worker misjudges distance and speed. They take shortcuts to finish the job. They can also fall into a microsleep, a few seconds of sleep they cannot control. On a forklift or a crane, a few seconds is enough to kill someone.

The WSH Council fatigue guidelines describe a fatal case. A forklift driver ran over a worker sleeping in a dark yard near midnight. Both had worked more than 14 hours that day. The driver had worked over 20 hours on two days the week before.

The guidelines also cite research on sleep loss. Losing two hours of sleep can impair you about as much as two to three bottles of beer.

What causes it

Your body runs on a daily clock. It wants sleep at night and dips again in the early afternoon. Night work fights that clock. Most adults need about 8 hours of sleep a day. Lost sleep builds into a debt that takes several days to repay.

• Work: long shifts, night shifts, too little time between shifts, poor rosters, short or missed breaks.
• The job itself: heavy physical effort, long periods of concentration, monotonous tasks.
• The workplace: heat, poor lighting and noise all make tiredness worse.
• Outside work: long travel to site, a second job, family demands, poor sleep in crowded quarters, sleep disorders, some medicines.

Spot the signs

Fatigue is easy to miss. Workers rarely say they are tired. Watch for changes in how a person acts, especially late in a shift or on nights.

• Yawning, heavy eyelids, nodding off during breaks or briefings.
• Irritability, or talking less than usual.
• Clumsiness, dropped tools, slow reactions.
• Forgetting instructions or steps they know well.
• Taking shortcuts or more risks than usual.

Order of controls

Fix the roster before you rely on coffee and willpower. The WSH Council guidelines give these scheduling measures.

• Remove night work where the task does not need to happen at night. Do complex jobs in the day.
• Avoid the low points. Keep safety-critical work out of 2am to 6am. The 2pm to 4pm dip matters too, to a lesser degree.
• Cap shift length at 12 hours including overtime.
• Leave enough recovery time. Finishing at 11pm and starting at 7am is too tight.
• Rotate forward, from morning to afternoon to night, if shifts must rotate. The guidelines give two to three nights in a row as a limit for 12-hour night shifts.
• Staff each shift properly so nobody carries extra load. Give more supervision at night and late in the shift.
• Fix the environment. Good lighting and a cooler work area help people stay alert.
• Plan rosters early and tell workers ahead of time so they can plan their sleep. Give transport home after long or night shifts.

Breaks and naps

Longer and harder shifts need more total break time. Set breaks in the work plan. Do not leave them to chance.

Give workers a proper place to rest. It should be clean, quiet, dim and not too hot. A worker who naps on the ground in a work area can be hit by a vehicle.

A short nap of 20 to 30 minutes restores alertness. Longer naps drop into deep sleep and leave people groggy. Give a nap time to wear off before safety-critical work resumes.

For monotonous work, short activity breaks help. Stand up, stretch, change posture.

What the rules require

There is no national standard on fatigue in Singapore. The WSH Council guidelines are advice. But the WSH Act still makes employers take reasonably practicable steps to keep work safe. The guidelines say this includes managing fatigue through shift planning and rest breaks. Fatigue belongs in your risk assessment like any other hazard.

Working hours are set by the Employment Act. MOM's page on hours of work, overtime and rest days sets out these rules for employees covered by Part 4 of the Act. Part 4 does not cover managers and executives.

• No more than 12 hours of work a day. The exceptions are an accident or threat of one, essential work for the community, defence or security, urgent work on machinery or plant, and an interruption nobody could foresee.
• Overtime is capped at 72 hours a month unless MOM grants an exemption.
• Shift workers can work up to 12 hours a day, if hours average no more than 44 a week over three weeks.
• No more than 6 hours in a row without a break, as a general rule.
• One rest day each week.

Build it into your system

The guidelines suggest a fatigue management programme inside your safety system. You do not need a thick manual. You do need a few working parts.

• Audit rosters and actual hours, including overtime, against your limits.
• Give workers a way to report fatigue without blame. Record fatigue-related near misses.
• Ask about hours and sleep in every incident investigation, especially for night incidents.
• Train supervisors and workers on the body clock, the signs of fatigue and what to do.
• Have a backup plan. Know who takes over when a worker is too tired to continue.
• Watch the trends: sick leave, turnover and injury claims can all point to a fatigue problem.

Common mistakes

These show up in fatigue-related incidents again and again.

• Paying incentives that push workers into excessive hours.
• Scheduling lifting, driving or hot work at 3am because the site is quiet.
• Rest areas too far away, so workers sleep beside the work.
• Ignoring the second job or the two-hour commute.
• Treating a worker who admits tiredness as weak instead of keeping them off risky tasks.
• Checking the roster but not the real hours worked.

Use it on site: the fatigue and shift work checklist and the toolbox talk to brief your crew.

Sources

1. WSH Guidelines on Fatigue Management, WSH Council.
2. Hours of work, overtime and rest days, Ministry of Manpower.

This is practical guidance, not legal advice. Laws and codes of practice change; always check the current official text and your site's own procedures.