Sleepiness and work: a safety and performance issue

Sleepiness doesn't stop the moment you get out of bed. It often follows a person throughout the day, including at work, with consequences that go well beyond a simple slump in the early afternoon.

A phenomenon affecting a large share of employees

In France, the annual survey by the Institut national du sommeil et de la vigilance (INSV) published in 2025 indicates that 43% of adults report having at least one sleep disorder: insomnia, sleep apnea, accumulated sleep debt. A growing share report feeling sleepy during the day. Occupational physicians deal with these situations daily, which translate concretely into reduced concentration, more errors, and lower productivity.

Work schedules play a major role here. According to the Direction de l'animation de la recherche, des études et des statistiques (DARES, the French labor ministry's statistics office), about 15% of French employees work nights, whether regularly or occasionally, a proportion that has risen markedly over about twenty years. Shifted schedules, very early in the morning or late in the evening, affect an even larger share of the working population. In the United States, the CDC estimates that about one worker in three sleeps less than 7 hours a night, with higher proportions in healthcare, transportation, and manufacturing. At the global level, the World Health Organization and the International Labour Organization estimated in 2021 that long working weeks, beyond 55 hours, were associated with about 745,000 deaths from stroke or heart disease in a single year, 2016. Lack of sleep is one of the mechanisms proposed to explain this link.

A recognized factor in workplace accidents

Sleepiness isn't just a matter of comfort or performance: it's also a safety issue. A meta-analysis published in 2014 (Uehli et al., Sleep Medicine Reviews), cited by the leading US occupational health agency (NIOSH), estimates that about 13% of workplace accidents are attributable to sleep problems. Shift work is particularly affected. According to the US Occupational Safety and Health Administration (OSHA), accident rates are about 18% higher on evening shifts and 30% higher on night shifts than on day shifts. The main cause: impaired reaction times and decision-making.

Shift length matters too. Work by British researcher Simon Folkard showed that risk rises with consecutive night shifts: the fourth consecutive night shift carries markedly higher risk than the first. Risk also rises with shift duration: by the twelfth hour of work, it is roughly twice as high as during the first eight. Working 12-hour days is associated with about a one-third increase in injury risk.

While these figures come from Anglo-American studies, they illustrate a reality that applies just as much to shift-work occupations in France: transport, healthcare, industry, security. In these occupations, alertness has to stay intact during hours when the body is biologically pushed toward sleep.

The risk doesn't end when the shift does. A study published in the New England Journal of Medicine in 2005 (Barger et al.), involving nearly 2,700 American medical residents, showed this clearly. Each extended shift scheduled in a given month raised the risk of a car crash on the drive home by about 16%. The commute home after a night shift is a particularly vulnerable moment.

Particularly exposed occupations

Certain occupations combine several risk factors: shifted schedules, long hours of driving or monitoring, direct responsibility for other people's safety. This is notably the case for professional drivers. In the 2026 survey by the INSV and the VINCI Autoroutes Foundation, 43% of people who work nights or shifted schedules reported having experienced an episode of drowsy driving in the past year, compared with about one driver in four across the general population.

Healthcare workers are another example: nurses, nursing assistants, and doctors string together night shifts and rotating schedules, with documented consequences for care errors and blood-exposure incidents. Others include security guards, pilots, air traffic controllers, train drivers, bakers, workers in 24/7 rotating-shift industries, and logistics staff.

Industrial history offers several reminders of this issue. Investigative commissions identified crew fatigue and lack of sleep as a contributing factor in several major disasters, including the Three Mile Island nuclear accident in 1979 and the 2005 explosion at BP's Texas City refinery, both occurring at the hours when human alertness is at its lowest.

Cognitive performance and decision-making

Beyond the risk of accidents, sleepiness impairs abilities that are less visible but just as important at work: concentration, working memory, reaction speed, and the quality of judgment in situations that require precision. Even moderate chronic sleepiness can have a real impact on the quality of work produced, without the person always connecting it to their sleep.

Laboratory research shows that not all functions are affected equally. Repetitive, monotonous tasks, such as monitoring a screen or proofreading a document, are the first to suffer: attention lapses in brief episodes, more frequent the greater the sleep debt. The ability to adapt to an unexpected situation, change strategy, or assess a risk also declines. Conversely, a sleep-deprived person can remain effective on a short, stimulating task, which creates a false impression of being in control.

Sleepiness also affects working relationships. Sleep deprivation makes people more irritable and less patient, and reduces the ability to read others' emotions. Sleepiness that drags on can therefore weigh on team atmosphere as much as on results. It is sometimes mistaken for burnout. The two can, in fact, coexist, and the hub's Am I burned out? test can help tell them apart.

What can be done

When sleepiness settles in over the long term at work, several approaches are worth exploring. The first is to objectively assess your level of sleepiness rather than relying on a vague impression of tiredness. The second is to identify a possible underlying cause: sleep apnea, circadian rhythm disorders linked to shift schedules, another sleep disorder. The third is to not hesitate to talk to occupational health services, which are specifically trained to support this kind of situation.

In France, night workers benefit from adapted individual follow-up by occupational health services, as required by the Labor Code, with a check-up before being assigned to the role. This follow-up can lead to changes in duties or schedules if the employee's health warrants it. Conversations with the occupational physician are covered by medical confidentiality: the employer is only informed of the fitness-for-work conclusions and any adjustments needed, not the diagnosis itself.

For people on shift schedules, a few strategies have proven useful. A short 20-minute nap before a night shift helps, as does a nap break during the shift when the organization allows it. Exposure to bright light at the start of a night shift promotes alertness, and wearing sunglasses on the drive home helps prepare for sleep. Finally, it helps to protect daytime sleep, with a dark, quiet, cool bedroom and a phone on silent. On the employer's side, schedule design matters: clockwise rotations (morning, then afternoon, then night) are better tolerated than the reverse, and it's best to limit the number of consecutive nights.

The Epworth Sleepiness Scale provides, in just a few minutes, a first objective assessment before taking that step.