"Short sleep duration (average ≤6 hours per 24-hour period) was reported by 30.0% of employed U.S. adults (approximately 40.6 million workers). Among workers in all shifts, workers in the middle age groups of 30-44 years (31.6%) and 45-64 years (31.8%) were significantly more likely than workers aged 18-29 years (26.5%) or ≥65 years (21.7%) to report short sleep duration," according to a 2012 analysis of National Health Interview Survey data.
Luckhaupt, S. E. (2012). Short sleep duration among workers - United States, 2010. Morbidity and Mortality Weekly Report, 61(16), 281-285. Retrieved from www.cdc.gov.