Los Angeles, Jun 4 (IANS): People who work in jobs that are physically demanding experience extremes of sleeping habits, according to a US research.

Such workers either experience shorter sleeping hours (fewer than six hours a night) or longer sleeping hours (longer than nine hours), said the research from a study from the Perelman School of Medicine at the University of Pennsylvania.

Since previous research has shown that people who report short or long sleep are more likely to have worse health over time, such as weight gain, heart disease and diabetes, the new study suggests that people's jobs may predispose them to unhealthy sleep patterns that could detrimentally affect their health, Science Daily reports.

According to the research team, possible explanations for the findings include: The higher demands of the job require longer hours, not allowing for a full night of sleep; Job-related stress is keeping people up at night; The physical demands of the job are causing people to stay awake.