Bern, Nov 23 (IANS): Insufficient sleep is one reason why poor people are more prone to heart disease, researchers have warned.

People with lower socioeconomic status sleep less for a variety of reasons: they may do several jobs, work in shifts, live in noisy environments, and have greater levels of emotional and financial stress, according to the study published in the journal Cardiovascular Research.

The study found that short sleep explained 13.4 per cent of the link between occupation and coronary heart disease in men.

"The absence of mediation by short sleep in women could be due to the weaker relationship between occupation and sleep duration compared to men," said study author Dusan Petrovic, from the University Centre of General Medicine and Public Health, Lausanne in Switzerland.

"Women with low socioeconomic status often combine the physical and psychosocial strain of manual, poorly paid jobs with household responsibilities and stress, which negatively affects sleep and its health-restoring effects compared to men," he said.

The study was part of the Lifepath project, and pooled data from eight cohorts totalling 111,205 participants from four European countries.

Socioeconomic status was classified as low, middle, or high according to the father's occupation.

A history of coronary heart disease and stroke was obtained from clinical assessment, medical records and self-report.

Average sleep duration was self-reported and categorised as recommended or normal sleep (six to 8.5), short sleep (six), and long sleep (more than 8.5) hours per night.

The contribution of insufficient sleep was investigated using a statistical approach called mediation analysis.

The study estimates the contribution of sleep to an association between the socioeconomic status and the coronary heart disease or stroke.

"Structural reforms are needed at every level of society to enable people to get more sleep. For example, attempting to reduce noise, which is an important source of sleep disturbances, with double glazed windows, limiting traffic, and not building houses next to airports or highways," he added.