Shift Work and Fatigue Statistics UK: Workforce and Risks

How many people work evenings, nights or shifts?

ONS counted 8.7 million people who usually worked in the evening or at night in 2022, including those who also worked during the day. This broad group represented 26.7% of the UK workforce.

HSE’s fatigue guidance separately cites more than 3.5 million shift workers, without stating the underlying estimate’s date. Shift working and usually working evenings or nights are different definitions, so these two figures do not form a time series.

How fatigue affects performance

HSE describes fatigue as reduced mental or physical performance associated with sleep loss, exertion or disruption of the body clock. Poorly designed schedules can impair attention, reactions and decision-making.

Fatigue assessment therefore needs to consider workload, shift length, breaks, overtime and recovery time. Compliance with working-time limits is one part of managing the risk.

Fatigue in high-risk rail incidents

ORR cites fatigue as a factor in 21% of high-risk rail incidents in RSSB’s 2022 evidence. It also identifies 17 RAIB recommendations about fatigue arising from incidents during 2010–2022.

The figures describe Great Britain’s rail sector. The first measures the share of a defined incident group; the second counts recommendations resulting from investigations.

Night work and longer-term health research

IARC classifies night shift work as Group 2A: probably carcinogenic to humans. Its assessment draws on limited human evidence for breast, prostate and colorectal cancers alongside animal and mechanistic evidence. This classification identifies a potential hazard rather than a fixed risk increase for every night worker.

A 2015 meta-analysis of shift-work exposure and diabetes found an overall adjusted odds ratio of 1.09, with stronger associations in some subgroups. The finding is an association across the included studies; it does not give an individual’s absolute probability of developing diabetes.

Night-work limits and rest entitlements

Adult night workers must usually work no more than eight hours per 24 hours on average, normally calculated over 17 weeks. Where the work involves special hazards or heavy physical or mental strain, the eight-hour limit applies within any 24 hours without averaging. Sector and role exceptions can apply.

Employers must offer free health assessments before night work and regularly afterwards. Suitable alternative work should be found where possible if night work affects health. Adults usually have 11 hours’ rest between working days; exceptions can require compensatory rest.

Designing rosters to reduce fatigue

HSE’s guidance addresses actual hours, overtime, consecutive shifts, breaks and job demands. It includes considering forward rotation and limiting demanding night shifts, while recognising that suitable arrangements differ between workplaces.

Compare planned rosters with the hours people actually work. Fatigue reports and incident records are most useful when interpreted alongside exposure: a shift with more staff, longer hours or more hazardous duties may produce more incidents for those reasons.

Frequently asked questions

How many UK workers usually work evenings or nights?

ONS estimated 8.7 million in 2022, or 26.7% of the workforce. Its definition includes people who usually work evenings or nights, whether or not they also work during the day.

Does an eight-hour night-work limit mean every eight-hour night shift is safe?

No. HSE says working-time compliance alone does not adequately manage fatigue. Workload, breaks, overtime and recovery also matter.

Does night work definitely cause cancer?

IARC classifies it as probably carcinogenic, Group 2A, with limited human evidence. The classification is not an individual diagnosis or a universal percentage risk.