A major new study of American workers and their sleep patterns has recommended later start times to improve on health.
Experts said 'delaying the morning start time of work,' or making it flexible, could have a major effect.
They found that for every hour that work was delayed, people got 20 minutes more sleep.
After analyzing results from 124,517 American adults on their sleep and work habits, as recorded in the American Time Use Surveys from 2003 to 2011, lead author Dr. Mathias Basner of the University of Pennsylvania Perelman School of Medicine and colleagues found an association between earlier starting times for work or school and less time spent sleeping.
'Results show that with every hour that work or educational training started later in the morning, sleep time increased by approximately 20 minutes,' the researchers said.
'Respondents slept an average of only 6 hours when starting work before or at 6 a.m. and 7:29 hours when starting work between 9 a.m. and 10 a.m.'
The new study shows that paid work time is the primary waking activity exchanged for sleep and suggests that chronic sleep loss potentially could be prevented by strategies that make work start times more flexible.
Results show that work is the dominant activity exchanged for less sleep across practically all categories.
Compared to normal sleepers, short sleepers who reported sleeping 6 hours or less worked 1.55 more hours on weekdays and 1.86 more hours on weekends or holidays, and they started working earlier in the morning and stopped working later at night.
The highest odds of being a short sleeper were found among adults working multiple jobs, who were 61 percent more likely than others to report sleeping 6 hours or less on weekdays.
Respondents who were unemployed, retired or absent from the labour force also obtained significantly more sleep and were less likely to be short sleepers.
'The evidence that time spent working was the most prominent sleep thief was overwhelming,' said lead author Dr. Mathias Basner, assistant professor of sleep and chronobiology in psychiatry at the University of Pennsylvania Perelman School of Medicine in Philadelphia.
Short sleepers also traveled more, started traveling earlier in the morning, and stopped later in the evening than normal sleepers.
The travel pattern, with peaks at 7 a.m. and 5 p.m., strongly suggests that the majority of travel time is associated with commuting.
According to Basner, the results point to several possible solutions for workers' lack of sleep.
'Potential intervention strategies to decrease the prevalence of chronic sleep loss in the population include greater flexibility in morning work and class start times, reducing the prevalence of multiple jobs, and shortening morning and evening commute times,' he said.
Short sleepers also traveled more, started traveling earlier in the morning, and stopped later in the evening than normal sleepers.
Results show that with every hour that work or educational training started later in the morning, sleep time increased by approximately 20 minutes.
Self-employed respondents with more flexible work times also obtained significantly more sleep than private sector employees and were 17 percent less likely to be a short sleeper.
Study results are published in the December issue of the journal Sleep.
'Getting at least seven hours of nightly sleep is essential to be at your mental, emotional and physical best for whatever you will pour yourself into, either at work or at home,' said American Academy of Sleep Medicine President Dr. Timothy Morgenthaler, who was not involved in the study.
