Yesterday, in honor of National Sleep Awareness Week, we blogged about sleep and work and the risks to workers, employers, and the public when workers’ hours and shifts do not allow for adequate sleep.   This blog provides a brief overview of some of the work that NIOSH intramural scientists are carrying out to better understand these risks and ways to prevent them.

Nurses/Reproduction Issues/Shift Work

NIOSH studies are examining shift work and physical demands with respect to adverse pregnancy outcome among nurses, specifically the association between work schedule and risk of spontaneous abortion, preterm birth, and menstrual function.  This research was the first to look at shift work and pregnancy in U. S. nurses.  NIOSH researchers are collaborating with the Harvard Nurses’ Health Study, which is the largest, ongoing prospective study of nurses. Results have shown that an increased risk of several reproductive outcomes, including spontaneous abortion, early preterm birth, and menstrual cycle irregularities, are related to shift work, particularly working the night shift. In addition, results show independent effects on reproductive outcomes from long working hours.  The study hopes to establish a cohort of over 100,000 female nurses of reproductive age.  As this longitudinal study progresses, there will be increased opportunity to study the impact of occupational exposures on a wide variety of chronic disease outcomes, including cancers and heart disease. 

Police/Sleep/Shiftwork/ Stress

A series of studies are being carried out to understand the connection between exposures to occupational stressors and health outcomes in police officers in Buffalo, New York. Early studies have already indicated that there are significant adverse health outcomes associated with sleep and shift work. One study found that the majority of officers reported feeling tired upon awakening (89.9%) and snoring (83.3%) (Charles et al, 2007a).  The prevalence of snoring was 26% higher in night shift workers compared to the other workers.  A 2009 published study found that officers who worked nights and either had less than 6 hours of sleep or worked more overtime had a greater risk of injury and metabolic syndrome compared to officers working the day shift. 

Trucking/Manufacturing/White Collar Workers

Several studies examining large samples of workers have been published or are currently in progress. Information on driver fatigue and the quality, location, and length of sleep has been collected in a large national  survey of long-haul truck drivers.  Results from this survey are being used to determine the extent of sleep disorders (including sleep apnea) drivers experience and their relationship to health conditions and crashes. A series of studies examining long work hours have been published. In healthy daytime workers, emotional fatigue was associated with a decline of function and quantity of Natural Killer cells, a white blood cell that is part of our first line of defense against cancer and viruses (Nakata et al., 2011, JOEM). A study found that long work hours combined with short sleep (less than 6 hours/day) or insufficient sleep was associated with depression, injury, and poor health that are largely associated with sleep problems rather than work hours itself (Nakata, 2011, J Clin Psychiat; Nakata, 2011, J Sleep Res; Nakata, 2011, Int J Public Health).  Among shift workers, those with low social support at work had two times higher prevalence of insomnia than those with high support even after considering the effects of workload (Nakata et al., J Human Ergol, 2002).   

Training

NIOSH scientists are developing and evaluating tailored training programs for managers and workers in manufacturing, mining, nursing, retail, and trucking to inform them of the importance of sleep and the risks linked to insufficient sleep, shift work, and long work hours and strategies to prevent these risks. 

• NIOSH has developed a comprehensive online training program for nurses. The program includes a short video and 12 modules. The training program is currently being pilot tested in senior nursing students and registered nurses enrolled in nursing graduate courses.
• For the trucking industry, NIOSH has developed two public service announcements to broadcast over the radio and two brochures to raise awareness of the risks of long work hours and shift work, as well as what actions they can take to help manage their risks. A website for trucking is also under development.
• For the mining industry, NIOSH is developing two presentations on shift work and sleep for mining trainers. A helmet sticker has also been developed to help further raise awareness of this issue.  
• NIOSH developed a series of six 30 minute webinars to educate workers and managers in manufacturing and retail about sleep.

Risk Assessment

NIOSH scientists are exploring statistical and epidemiological issues to lay the groundwork for the quantitative risk assessment of work hours related to occupational illness and injury outcomes.  This approach will use work hour data that is collected over a period of time.  The project staff will examine how work hour patterns relate to a range of adverse outcomes, including, but not limited to, errors in the workplace.  This work is in its early stages, but is part of the effort to develop a quantitative risk assessment of work hours that can be used to refine policy and recommendations targeted at reducing illness and injury associated with long work hours, shift work, and other irregular work schedules.

As we continue to learn and develop more resources to help address the risks of shift work and long work hours and sleep, we will share these findings on our web page, the NIOSH topic page on Work Schedules: Shift Work and Long Work Hours.

Reference list and selected reading

—Claire Caruso, PhD, RN; Luenda Charles, PhD; Tina Lawson, PhD; Akinori Nakata, PhD; Karl Sieber, PhD; Sudha Pandalai MD, PhD; and Ted Hitchcock, PhD.

Drs. Caruso, Hitchcock an Nakata work in the  Organizational Science and Human Factors Branch  in the NIOSH Division of Applied Research and Technology

Dr. Pandalai is a medical officer in the Risk Evaluation Branch of NIOSH’s Education and Information Division.

Dr. Charles is an epidemiologist in the NIOSH Health Effects Laboratory Division.

Dr. Lawson is a research epidemiologist in the Industrywide Studies Branch of NIOSH’s Division of Surveillance, Hazard Evaluations, and Field Studies

Dr.  Sieber is a Research Health Scientist with the Surveillance Branch of the NIOSH Division of Surveillance, Hazard Evaluations, and Field Studies.