An increasing number of studies show that chronically restricted sleep to less than seven hours per day impairs performance, increases the risk for errors and accidents, and is associated with negative health consequences like obesity, diabetes, and cardiovascular disease. Yet nearly 40 percent of adults in the United States report sleeping less than seven hours on weekday nights, and 15 percent report getting less than six hours. Little is known about the factors that put individuals at risk for being among this group of “short sleepers,” nor about which waking activities are most apt to be "traded" for less sleep.

Now, research from the University of Pennsylvania’s Perelman School of Medicine published in the December issue of the journal Sleepidentifies characteristics and behaviors associated with short sleep that could be targeted to reduce the negative health consequences linked to short sleep. The Penn Medicine team analyzed data from a representative sample of 124,517 Americans 15 years and older who participated in the American Time Use Survey (ATUS) between 2003 and 2011.

“Intervention programs and educational campaigns can only be successful if they target the right behavior, at the right time of day, and in the right population. Time use surveys provide these crucial insights that cannot be derived from experimental or epidemiological studies,” said lead author Mathias Basner, MD, PhD, MSc, assistant professor of sleep and chronobiology in Psychiatry. "The evidence that time spent working was the most prominent sleep thief was overwhelming," Basner said. "It was evident across all sociodemographic strata and no matter how we approached the question." 

Individual characteristics associated with paid work, including long commute times, were consistently associated with short sleep. Short sleepers started working earlier in the morning and stopped working later at night. With every hour that work or educational activities started later in the morning, sleep time increased by approximately 20 minutes. Those working multiple jobs were 61 percent more likely to be short sleepers. Moreover, self-employed respondents with more flexible work times were less likely to be short sleepers on weekdays, and average sleep time was higher during the economic crisis years with lower employment rates.

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