Sleep that is extremely disrupted or that goes on too long could mean a loss of nine months from working life after the age of 50, a study has found.

It also found that women with no sleep disturbances had a longer working life from 50 to 68 than their male equivalents.

Compared with participants who had no sleep disturbances, those with moderate sleep disturbances could expect to work nearly five fewer months within that age range and those with severe sleep disturbances eight fewer months, regardless of gender or job type.

The research, conducted by a team at the University of Turku in Finland, used data from the Finnish Public Sector (FPS) study and the Health and Social Support (HeSSup) study and surveyed participant’s sleeping habits after turning 50.

Nightly sleep length was categorised as short (under seven hours), mid-range (between sevenand 8.5 hours), or long (nine hours or more), and sleep disturbances were defined as difficulties falling asleep and difficulty staying asleep, waking up too early, and nonrestorative sleep during the four weeks preceding the survey.

Short and mid-range sleep length were both associated with a working life expectancy of 13 years and two months after 50, according to the research, while long nightly sleep length was associated with a working life expectancy of 12 years and five months.

The longest working life expectancy, almost 14 years, was observed among professional women with no sleep disturbances. The shortest was observed among men in routine jobs with severe sleep disturbances, of nearly 12 and a half years.

Previous studies have suggested that one in three workers across the UK are experiencing a chronic lack of sleep.

The study’s lead investigator, Dr Saana Myllyntausta, of the department of psychology and speech-language pathology at the University of Turku, said: “It was surprising that we found no differences between those with short sleep duration and those with mid-range sleep duration, that is 7–9 hours per night, which is considered the optimal amount of sleep.

“Short sleep duration has been previously linked in some studies to, for example, earlier retirement. Long sleep duration, on the other hand, was associated with shorter working life expectancy, and it has also been linked to poorer health outcomes, which might explain the shorter working career.”

She added: “Our findings highlight the importance of supporting sleep health and treating sleep problems, particularly among those with low socioeconomic status, during middle age.

“It’s important to support sleep in the working life. For example, interventions aimed at treating insomnia provided by occupational health services or workplace interventions, such as educational or health promotion interventions for sleep have been found in previous studies to be effective ways to support sleep among working-age adults.”

The study concluded: “Promoting sleep health and providing support for managing sleep disturbances at midlife may be especially important for those with a lower socioeconomic status when aiming to increase workforce participation with advancing age.

“This could include cognitive behavioural therapy for insomnia delivered by occupational health services or workplace interventions, such as educational or health promotion interventions for sleep.”

The researchers also acknowledged that they were not able to account for other potentially influential factors, such as physical and mental health, underlying health conditions, risky health behaviours, and working conditions like shift work.