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Abstract #165199

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Michael Smolensky, PhD, School of Public Health, University of Texas Health Sciences Center at Houston, 1200 Hermann Pressler Dr., RAS W606, Houston, TX 77030, 713-500-9237, msmolensky@houston.rr.com

All life forms evolved under and adapted to annual, lunar and 24-hour (h) natural environment photoperiodicities. The biology of the diurnal human species is geared for activity during the light of day and sleep during the dark of night. Since the invention of the incandescent light bulb, modern technologies have created an unnatural environment in which moderate to bright light exposure may be present throughout the entire 24h. Artificial light enables extension of the normal diurnal span of human activity and productivity, but it also can alters biology, especially the 24h sleep-wake cycle. The consequence is reduced nighttime sleep of adults and children. The 2005 National Sleep Foundation survey found ~25% of Americans sleep <7 h/weekday. Such sleep loss can result in significant decrease in prolactin, melatonin, growth and (ghrelin which stimulates and leptin which inhibits) appetite hormones. Artificial light and modern technologies have enabled the growth of night and rotating shift-work schedules, currently involving 15-20% of the US workforce. These work schedules severely compromise sleep duration and quality. Night work is a risk factor for industrial accidents and injuries and several medical conditions, including cancer especially in women. Overall, sleep loss and nighttime light exposure pose serious, but as yet unappreciated, public health problems.

Learning Objectives:

• Describe the basic functions of the 24h circadian rhythm and its importance in basic biological processes.
• Identify the effects of altered or shifted 24h rhythm on sleep and other biological processes.
• List the effects of night or shift work on health
• Discuss possible policy implications of the health risks of night and shift work and of nighttime light exposure.

Keywords: Occupational Health, Injury Risk

Presenting author's disclosure statement:

Any relevant financial relationships? No
Any institutionally-contracted trials related to this submission?

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

• Slides (pdf) or Handout