September 25 2007 - Research from the University of Pennsylvania published in SLEEP has
found that work time is the largest influence on how long an individual sleeps on both work and leisure days. The more
hours worked the less sleep achieved.
Dr Mathias Basner analyzed a telephone survey of 47 731 respondents between 2003 and 2005 to the
American Time Use Survey (a continuous study sponsored by the Bureau of Labor Statistics and conducted by the U.S.
Census Bureau). The survey asked people how they had spent their time in the 24 hours up to 4.00am on the day
interviewed.
Analysis revealed that the majority of waking activities were inversely related to sleep time.
Compared to the average sleeper, respondents who slept up to 4.5 hours worked an average of 93 minutes more on
weekdays and 118 minutes more on weekends and those who slept a minimum of 11.5 hours worked an average of 143
minutes less on weekdays and 71 minutes less on weekends. The report highlights expert recommendations that adults
get seven-to-eight hours of sleep a night.
Mathias Basner said:
"These cross-sectional results in a nationally representative sample suggest that compensated work
time is the most potent determinant of sleep time, in which case work time should be considered an important factor
when evaluating the relationship between sleep time and morbidity and mortality."
Another key finding was that travel time (including commute to work) on both weekdays and weekends
unexpectedly proved to be the second most significant factor after work time. The author suggests further research
is indicated into how sleep time is affected by earlier starts and/or later returns as people travel longer distances
or cope with inadequate transport infrastructure and traffic congestion. In addition little is known about the
impact of non-commute travel on sleep time.
The study found that there was a moderate relationship between short sleep and time spent on
socializing, relaxing and leisure. Respondents in this category also spent more time on education and household
activities and those with very short sleep times spent more time watching TV. Waking activities decreased with
increasing sleep time with the exception of watching TV.
The study found little difference between work and non-work days except that compared to respondents
with average sleep times, short sleepers spent less time watching TV on weekends, and long sleepers spent less time on
socializing, relaxing and leisure activities. The balance between sleep time and waking activities was influenced by
age and gender. Work time was maximal for respondents aged 45-54 years; sleep time increased for younger and older
age groups.