Karoshi: Death From Overwork and What Other Countries Can Learn

Karoshi is a Japanese word meaning death from overwork. The International Labour Organization (ILO) describes it as a sociomedical term rather than a medical one: deaths or lasting disability from strokes, heart attacks or heart failure made worse by a heavy workload and long hours. Japan treats such deaths as work-related and compensates the families, and it gives suicide linked to overwork its own word, karojisatsu.¹

That gives Japan an unusually long official record of how work can kill, and the record has changed shape. In Japan’s compensation figures, heart and brain cases have stayed near 200 a year in recent years, while work-related mental-disorder cases more than tripled since 2010.² Japan’s lessons travel: record real hours, guard the rest between shifts, and treat harassment as part of the same hazard. Overwork is one strand of work-life balance as researchers measure it.

Parts of this article discuss suicide. If you are struggling now, the help section just before the article’s close lists where to turn, starting with your local emergency number.

What karoshi means, and where the word came from

Karoshi entered Japanese occupational medicine in 1978 with a report on a series of cases presented at a meeting of the Japan Association of Industrial Health. According to the ILO’s 2013 case study, the media took up the word because it stressed sudden deaths from overwork that ought to be compensated.¹

In 1988 volunteer lawyers opened the first overwork-death telephone hotline for workers and families, and bereaved families formed a national association three years later, according to a 2024 review in the journal of Japan’s National Institute of Public Health.³

Because karoshi is a judgment about cause rather than a diagnosis, a sales manager who has a stroke at his desk dies, medically, of a stroke. Whether the death was karoshi is decided later, by a labour office or a court, from evidence about his hours and workload. In a country without such a system, nobody may ever ask whether work played a part, so the most useful record is often the one a worker keeps: dates, start and finish times, and missed days off.

What is the difference between karoshi and karojisatsu?

Karoshi, in its narrow sense, is death from heart or brain disease caused by overwork; karojisatsu is death by suicide after a mental disorder caused by overwork and stress at work. The ILO dates karojisatsu as a social issue in Japan to the late 1980s and lists long hours, heavy workloads, little control over the job, conflict and job insecurity as psychosocial hazardspsychosocial risk: A feature of how work is designed, organized or managed that can harm mental or physical health, such as heavy workload, low control, poor support, bullying or job insecurity. Guidance puts changing these conditions ahead of asking workers to cope better.Full entry in the glossary behind it.¹

The two tend to strike different people. The 2024 review describes heart and brain deaths falling mostly on men in middle age and later, and overwork suicides mostly on workers in their twenties and thirties. Every heart and brain death in the cases it summarizes involved more than 60 hours of overtime a month, while a quarter of the suicides involved less; the case reports it cites also point to low control over the job, little support and harassment.³

Suicide never has a single cause, and a finding that a death was work-related does not say otherwise. It is a legal judgment that work was a major contributor, made so that families can be compensated and employers held to account.

1. Karoshi in the narrow sense: death from a stroke, heart attack or other heart or brain disease brought on by an excessive workload
2. Karojisatsu: death by suicide after a mental disorder caused by strong psychological strain at work
3. Illness without death: the same heart or brain diseases and mental disorders when the worker survives, which the law also covers

Japan’s 2014 Act on Promotion of Measures to Prevent Karoshi covers all three forms in the drawing, including illness that does not end in death.³ For a manager, a quiet, struggling new hire deserves as much attention as an exhausted veteran.

How Japan decides a death was caused by overwork

In Japan, families apply for workers’ compensation, and labour offices judge each claim against national criteria. For heart and brain disease, the criteria treat the link to work as strong when someone worked about 100 hours of overtime in the month before falling ill, or more than about 80 hours a month on average over the preceding two to six months, according to a 2026 summary by the Japan Institute for Labour Policy and Training (JILPT). The criteria already weighed long periods on duty and irregular or night shifts, and a 2021 revision added working without days off and short gaps between shifts. A delivery driver whose overtime fell short of that line, but who often slept only a few hours between a late finish and an early start, can now have those conditions assessed together. Hours still dominate, though: more than two-thirds of the heart and brain cases compensated in fiscal 2024 involved average overtime of 80 hours a month or more.²

The compensation line marks where Japan’s compensation system presumes harm, not a level below which work is safe. The 2024 review notes that Japan’s 2006 guidance on preventing health damage from overwork already linked a rising risk of brain disease to overtime of 45 hours a month or more.³ Anyone tracking their own overtime can treat that lower prevention figure as the warning sign; the compensation line describes a month already far past it.

Myth

Overtime below Japan's 80-hour line is safe.

Fact

The 80-hour line is where compensation presumes harm. Japan's own prevention guidance places the start of rising risk much lower.

How many people die from karoshi each year?

Japan publishes its compensated cases every year, and those figures are one of the few annual counts of deaths from overwork anywhere. They are a floor: they include only claims that families make and win.

The study

Moderate evidence

Japan's compensated overwork cases, fiscal 2024

Japan compensated 241 cases of heart or brain disease caused by overwork in fiscal 2024, 67 of them deaths. It also recognized 1,055 cases of work-related mental disorder, 88 of them suicides, up from 308 mental-disorder cases in fiscal 2010.²

The suicide count includes attempts. The growth in mental-disorder cases does not necessarily mean overwork got worse. Japan revised its criteria several times, adding power harassment, bullying by people with authority over the worker, in 2020; the review reports that cases caused by long hours have fallen in recent years while certified cases caused by bullying and harassment have been rising. It also names a gap at the start of the process: many doctors do not know the compensation system, one reason, the review says, that certification rates for overwork suicide stay low.³

Worldwide, the most-cited figure is a model, not a count. For 2016, WHO and the ILO attributed roughly 745,000 deaths from stroke and ischemic heart disease to working 55 or more hours a week, and urged governments to ban mandatory overtime and set maximum limits on working time.⁴ That estimate rests on assumptions experts still argue over, set out in the evidence on long hours, heart disease and stroke. When a karoshi figure appears in the news, check whether it is a count of compensated cases or a model’s estimate.

What has Japan done to prevent karoshi?

Japan’s prevention law came from bereaved families, who gathered signatures with lawyers and academics until a cross-party caucus of Diet members took up the bill. The 2014 Act on Promotion of Measures to Prevent Karoshi requires the government to research deaths from overwork and report on them in an annual white paper.³

Courts had set the employer’s duty earlier. Ruling in 2000 on the death of a young Dentsu employee who had worked constant long overtime, Japan’s Supreme Court held the company responsible and recognized that fatigue and strain from long hours can damage health and lead to death.³

The best-known case came later, at the same company. Matsuri Takahashi, a new recruit at Dentsu, Japan’s largest advertising agency, died by suicide in December 2015; Reuters reported that she had logged 105 hours of overtime in one month and then become depressed. The government recognized her death as karoshi, Dentsu’s president resigned, and her mother said she wanted to change how every working person in Japan thinks about work.⁵ In 2017 a Tokyo court fined Dentsu for failing to prevent illegal overtime.³

1. 1978Karoshi first reported at a Japanese occupational health meeting
2. 1988Lawyers open the first overwork-death hotline
3. 2000Supreme Court rules in the first Dentsu case
4. 2014Act on Promotion of Measures to Prevent Karoshi
5. 2018Work-style reform law sets overtime caps
6. 2024Caps extended to drivers, doctors and construction

Until the 2018 work-style reform, Japan had no legal limit on overtime, only administrative guidance. The reform also made employers monitor actual working hours and encouraged a rest period between one day’s work and the next.⁶ The standard cap is 45 hours of overtime a month. Under special agreements, overtime and holiday work may go higher but must stay under 100 hours in any month and average no more than 80 hours over any two to six months; breaking the caps can bring a fine or a prison term. Since April 2024 the caps also cover construction, and drivers and doctors have their own higher limits.⁷ From September 2026, AFP reported, labour inspectors stopped pressing firms with special agreements to stay within the standard cap; the labour ministry said it would still give guidance where health risks are high.⁸

Whether the caps have saved lives has not been measured. The share of employees working 60 hours a week or more has fallen, yet recognized mental-disorder cases kept rising.³ JILPT argues that the caps need active monitoring, and that the pressures behind long hours, such as client demands and sales quotas, need tackling as well.²

Does death from overwork happen outside Japan?

Yes, though few countries name or count it. South Korea calls it gwarosa.⁹ A 2019 review in the Journal of Occupational Health describes Korea as one of the few countries that compensate heart and brain disease and mental disorders linked to long hours or heavy workloads. In 2018 Korea cut the legal maximum week to 52 hours, and when the review was written, an average of more than 60 hours a week over the previous three months was enough on its own to recognize a heart or brain disease as work-related. In the suicide claims it reviewed from 2016 and 2017 the stress most often cited was conflict with a supervisor, including harassment.¹⁰

China’s word is guolaosi, and its picture is less clear. A figure of about 600,000 deaths a year circulates widely, but a 2015 study by economists at Germany’s University of Hohenheim notes that it comes from a newspaper report. Their own analysis of a long-running Chinese health survey linked long hours to only slightly higher chances of high blood pressure and poorer self-rated health.¹¹ It measured health rather than deaths, so it cannot settle the question. The law is moving regardless: in 2021 China’s Supreme People’s Court said that the “996” schedule, nine in the morning to nine at night, six days a week, is illegal, NPR reported.¹²

Elsewhere, deaths from overwork mostly go unrecorded as such. Across the European Union, the 2003 Working Time Directive caps average weekly hours at 48, overtime included, and requires at least 11 consecutive hours of daily rest.¹³ Working-time law differs from country to country, so readers outside Japan should check their own country’s rules and the labour inspectorate or union that enforces them.

What other countries can learn from Japan

Five lessons from Japan carry over to governments, employers and team managers anywhere.

• Record real hours. A shared log of actual start and finish times, evening messages included, is the cheapest version of the monitoring Japan’s 2018 reform demanded.
• Give limits teeth. Until 2019 Japan relied on guidance without penalties, and WHO and the ILO urge governments to set maximum limits on working time.
• Protect the gap between shifts. A weekly total can look acceptable while a late finish and an early start leave only a few hours for sleep; Japan’s 2021 criteria count short gaps and long runs without a day off as added strain.
• Treat harassment as part of the same hazard. Japan’s criteria now include power harassment, and Korean suicide claims most often cite conflict with a supervisor.
• Make cases visible. Japan knows its numbers because it keeps compensation records and publishes an annual white paper.

Where to turn, and how urgently

Our arrangement by urgency draws on the organizations cited.

• Now: dial your local emergency number if anyone’s life is in immediate danger, including your own because of thoughts of suicide or self-harm. Find A Helpline, listed by the International Association for Suicide Prevention, covers more than 150 countries with free, confidential helplines.¹⁴ In the US, for instance, 911 is the number for emergencies, and the 988 Suicide & Crisis Lifeline can be reached by phone or text;¹⁵ in the UK, NHS advice when a life is at risk is 999 or the nearest A&E, and Samaritans can be phoned on 116 123.¹⁶ Signs of a stroke or heart attack that come on suddenly need the emergency number too.
• Soon, within a few weeks: see a doctor when worry, low mood or broken sleep hangs on, and check in with a colleague who seems withdrawn.
• Routine: if long weeks have become normal, mention them at your next health check and keep your own log of hours; a Japanese compensation claim rests on exactly that kind of evidence. A labour inspectorate, union or employment lawyer in your own country can answer legal questions.

When the hours come from an inner drive rather than a manager, the signs that hard work has turned into workaholism are worth knowing.

The bottom line

Japan’s karoshi cases show work harming health through ordinary routines: years of overtime, short nights and pressure from above. Most countries never count that cost, so start with your own team. Record its real hours for a month, check the gaps between shifts, and take any run of very long weeks to a manager, occupational health service or union.