Sheryll Soriano, MD

Since the use of oil burning lamps, followed by the invention of the light bulb by Thomas Edison, there has been a steady growth of nocturnal work. With the increasing demand worldwide to sustain our 24-hour society, it has been estimated that nearly 20% of the labor force worldwide involves work shifts outside the traditional 8:00 AM to 5:00 PM workday (Valentina et al. Sleep. 2014;37[3]:545). Leading this trend is the United States (as seen in the Figure). Shift work is even common in occupations that directly affect the health and safety of others, such as transportation and health care.

Shift work can cause a disruption of our circadian sleep-wake pattern and can often lead to sleep deprivation. Shift work disorder (SWD) is established when this misalignment between the timing of the sleep/wake cycle causes sleep disturbance, insomnia, sleepiness, fatigue, and impaired daytime function. The 2008 Sleep in America Poll assessed sleep and the workplace. The poll found that 58% of shift workers (defined as workers who start their job after 6:00 PM but before 6:00 AM) reported less than 6 hours in bed on workdays compared with 13% of nonshift workers. Shift workers worked more hours per week, were more likely to have other sleep disorders, and were more likely to drive drowsy. Recently reported cross-sectional data from the population-based Survey of the Health of Wisconsin (SHOW), collected from 2008 to 2012, showed that shift workers are more commonly men, minorities, and with lower levels of education (Givens et al. Sleep Health. 2015;1:115).

Shift work is more prevalent in blue-collar workers. However, white-collar nocturnal work is increasing as well. According to the US Bureau of Labor Statistics, between 1991 and 1997, there was an 11% increase in the number of white-collar employees working nights compared with only a 6% increase among blue-collar employees (Mcmenamin, Monthly Labor Review. 2007;Dec:3).

Work hours in the United States and elsewhere.

(adapted from Hamermesh et al. 2014. Long work weeks and strange hours. National Bureau of Economic Research.)

A potential health risk

Shift workers and those with SWD may be at greater risk for many health concerns. The SHOW data found shift workers to be more overweight than traditional schedule workers and reported more sleep problems, such as insomnia symptoms, insufficient sleep, and sleepiness. Shift workers have an increased risk of sleep disorders, cardiovascular disorders, obesity, and cancer.

Regarding cardiovascular disorders, shift work has been associated with coronary artery disease, hypertension, and cardiovascular death. The risk of death from heart disease was 19% higher among those who worked rotating night shifts for 6 to 14 years and 23% higher for those who worked rotating night shifts for 15 or more years according to the Nurses’ Health Study (Gu et al. Am J Prev Med. 2015;48[3]:241). While numerous studies have suggested higher prevalence of cardiovascular disease among shift workers, a clear causal pathway has not been established. Possible explanations for the increased cardiovascular disease include circadian stress along with behavioral changes, such as decreased physical activity and dietary changes in night shift workers. Shift work and sleep deprivation can lead to insulin resistance and type 2 diabetes, which can further increase cardiovascular risk. Other theories suggest physiologic stress, such as autonomic dysfunction, cortisol dysregulation affecting inflammation, or endothelial dysfunction.

Shift work has recently been associated with malignancy. Most notably, shift work has been associated with breast cancer. This risk appears to be greatest with prolonged rotating night shift early in one’s career (Schernhammer. Occup Environ Med. 2014;71[1 Suppl]:A121). The relationship between shift work and breast cancer is likely related to the changes in the circadian melatonin levels due to nocturnal exposure to light through multiple pathways (Hill et al. Endocr Relat Cancer. 2015;22[3]:R183). Recent data from the Nurses’ Health Study report a 25% increased risk of lung cancer among women working rotating shifts for more than 15 years compared with those working no night shifts. There is limited and inconsistent evidence for an association between shift work and prostate and colon cancers.

Irregular work hours not only result in physiologic stress but also psychosocial stress. With greater difficulties controlling personal hours, decrease work-life balance, and insufficient recovery sleep, family and social relationships are vulnerable to deterioration. This chronic “social jet lag” is associated with sleep deprivation, absenteeism, and depression.

Working during our circadian-predicted sleep phase can be associated with sleepiness at work. Risk for errors and accidents appear to be higher in shift workers with nearly three-fold increased risk of occupational and commute-to-home accidents compared with day workers (Swanson et al. J Sleep Res. 2011;20[3]:487). There is reported increased risk of motor vehicle accidents in health-care workers and police and commercial drivers working nights compared with those that do not work night shifts (Wright et al. Sleep Med Rev. 2013;17[1]:41). Risk of vehicular, aviation, and industrial accidents are highest at night, especially in the early morning hours.

What can we do?

As health-care providers treating sleep disorders, we commonly encounter shift workers and SWD. It is our responsibility to identify these at-risk patients and provide early intervention. Optimally, shift workers should attempt to sleep immediately after their night shift. Promoting good sleep hygiene is essential; restricting caffeine and alcohol consumption prior to bedtime, and turning off phones and other electronic devices during daytime sleep prevents disturbance. It is also important to educate family members regarding the need for protected sleep time for shift workers.

Administration of melatonin prior to daytime sleep may help to phase-shift the sleep period and provide a soporific effect. However, the data have not definitively supported improvements in sleep with morning (AM) melatonin use. Appropriately timed light exposure is critical to adaptation to a nocturnal schedule. Use of bright light during the first half of the night shift and increasing outside light exposure in the evening prior to starting one’s shift can phase delay the circadian pacemaker. Likewise, avoiding bright light on the ride home and in the morning is necessary to fully adapt to a night schedule. This can be done with use of dark sunglasses on the ride home. The scheduled daytime sleep period should be done in a dark room.

Ideally, those working night shifts should maintain their nocturnal schedule even on days off to allow them to stay in circadian phase. However, this is often not practical with family and personal responsibilities. Adjuncts to optimize workplace alertness and safety may be used. Caffeine use may enhance alertness during the night shift. Napping in the afternoon before starting a night shift and for brief periods throughout the night can be effective in improving alertness. More workplaces are providing sleep rooms to facilitate naps during work hours.

A final option to promote sleep and optimize alertness is with the aid of pharmaceuticals. Hypnotic medications may be used to promote daytime sleep among night shift workers with persistent difficulty initiating sleep and adjusting their circadian phase. However, carryover of sedation to the nighttime shift with potential adverse consequences for nighttime performance and safety must be considered. The nonamphetamine wakefulness promoting medications, including modafinil and armodafinil, can enhance alertness during the night shift for SWD. Their use in SWD is studied in clinical trials and is currently approved by the FDA for this indication.

Shift work is unavoidable in our present 24-hour society; therefore, a substantial proportion of the population is at risk for SWD. Cessation of shift work is curative but may not be an option. All shift workers will likely benefit from education about ways to promote circadian adaptation, increase wakefulness, improve sleep hygiene, increase sleep duration, and promote good health practices. Clinical practice guidelines for shift work and SWD are founded on evidence-based medicine.

Dr. Soriano and Dr. Das are with the Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine; The Ohio State University; Columbus, Ohio.

Since the use of oil burning lamps, followed by the invention of the light bulb by Thomas Edison, there has been a steady growth of nocturnal work. With the increasing demand worldwide to sustain our 24-hour society, it has been estimated that nearly 20% of the labor force worldwide involves work shifts outside the traditional 8:00 AM to 5:00 PM workday (Valentina et al. Sleep. 2014;37[3]:545). Leading this trend is the United States (as seen in the Figure). Shift work is even common in occupations that directly affect the health and safety of others, such as transportation and health care.

Shift work can cause a disruption of our circadian sleep-wake pattern and can often lead to sleep deprivation. Shift work disorder (SWD) is established when this misalignment between the timing of the sleep/wake cycle causes sleep disturbance, insomnia, sleepiness, fatigue, and impaired daytime function. The 2008 Sleep in America Poll assessed sleep and the workplace. The poll found that 58% of shift workers (defined as workers who start their job after 6:00 PM but before 6:00 AM) reported less than 6 hours in bed on workdays compared with 13% of nonshift workers. Shift workers worked more hours per week, were more likely to have other sleep disorders, and were more likely to drive drowsy. Recently reported cross-sectional data from the population-based Survey of the Health of Wisconsin (SHOW), collected from 2008 to 2012, showed that shift workers are more commonly men, minorities, and with lower levels of education (Givens et al. Sleep Health. 2015;1:115).

Shift work is more prevalent in blue-collar workers. However, white-collar nocturnal work is increasing as well. According to the US Bureau of Labor Statistics, between 1991 and 1997, there was an 11% increase in the number of white-collar employees working nights compared with only a 6% increase among blue-collar employees (Mcmenamin, Monthly Labor Review. 2007;Dec:3).

Work hours in the United States and elsewhere.

(adapted from Hamermesh et al. 2014. Long work weeks and strange hours. National Bureau of Economic Research.)

A potential health risk

Shift workers and those with SWD may be at greater risk for many health concerns. The SHOW data found shift workers to be more overweight than traditional schedule workers and reported more sleep problems, such as insomnia symptoms, insufficient sleep, and sleepiness. Shift workers have an increased risk of sleep disorders, cardiovascular disorders, obesity, and cancer.

Regarding cardiovascular disorders, shift work has been associated with coronary artery disease, hypertension, and cardiovascular death. The risk of death from heart disease was 19% higher among those who worked rotating night shifts for 6 to 14 years and 23% higher for those who worked rotating night shifts for 15 or more years according to the Nurses’ Health Study (Gu et al. Am J Prev Med. 2015;48[3]:241). While numerous studies have suggested higher prevalence of cardiovascular disease among shift workers, a clear causal pathway has not been established. Possible explanations for the increased cardiovascular disease include circadian stress along with behavioral changes, such as decreased physical activity and dietary changes in night shift workers. Shift work and sleep deprivation can lead to insulin resistance and type 2 diabetes, which can further increase cardiovascular risk. Other theories suggest physiologic stress, such as autonomic dysfunction, cortisol dysregulation affecting inflammation, or endothelial dysfunction.

Shift work has recently been associated with malignancy. Most notably, shift work has been associated with breast cancer. This risk appears to be greatest with prolonged rotating night shift early in one’s career (Schernhammer. Occup Environ Med. 2014;71[1 Suppl]:A121). The relationship between shift work and breast cancer is likely related to the changes in the circadian melatonin levels due to nocturnal exposure to light through multiple pathways (Hill et al. Endocr Relat Cancer. 2015;22[3]:R183). Recent data from the Nurses’ Health Study report a 25% increased risk of lung cancer among women working rotating shifts for more than 15 years compared with those working no night shifts. There is limited and inconsistent evidence for an association between shift work and prostate and colon cancers.

Irregular work hours not only result in physiologic stress but also psychosocial stress. With greater difficulties controlling personal hours, decrease work-life balance, and insufficient recovery sleep, family and social relationships are vulnerable to deterioration. This chronic “social jet lag” is associated with sleep deprivation, absenteeism, and depression.

Working during our circadian-predicted sleep phase can be associated with sleepiness at work. Risk for errors and accidents appear to be higher in shift workers with nearly three-fold increased risk of occupational and commute-to-home accidents compared with day workers (Swanson et al. J Sleep Res. 2011;20[3]:487). There is reported increased risk of motor vehicle accidents in health-care workers and police and commercial drivers working nights compared with those that do not work night shifts (Wright et al. Sleep Med Rev. 2013;17[1]:41). Risk of vehicular, aviation, and industrial accidents are highest at night, especially in the early morning hours.

What can we do?

As health-care providers treating sleep disorders, we commonly encounter shift workers and SWD. It is our responsibility to identify these at-risk patients and provide early intervention. Optimally, shift workers should attempt to sleep immediately after their night shift. Promoting good sleep hygiene is essential; restricting caffeine and alcohol consumption prior to bedtime, and turning off phones and other electronic devices during daytime sleep prevents disturbance. It is also important to educate family members regarding the need for protected sleep time for shift workers.

Administration of melatonin prior to daytime sleep may help to phase-shift the sleep period and provide a soporific effect. However, the data have not definitively supported improvements in sleep with morning (AM) melatonin use. Appropriately timed light exposure is critical to adaptation to a nocturnal schedule. Use of bright light during the first half of the night shift and increasing outside light exposure in the evening prior to starting one’s shift can phase delay the circadian pacemaker. Likewise, avoiding bright light on the ride home and in the morning is necessary to fully adapt to a night schedule. This can be done with use of dark sunglasses on the ride home. The scheduled daytime sleep period should be done in a dark room.

Ideally, those working night shifts should maintain their nocturnal schedule even on days off to allow them to stay in circadian phase. However, this is often not practical with family and personal responsibilities. Adjuncts to optimize workplace alertness and safety may be used. Caffeine use may enhance alertness during the night shift. Napping in the afternoon before starting a night shift and for brief periods throughout the night can be effective in improving alertness. More workplaces are providing sleep rooms to facilitate naps during work hours.

A final option to promote sleep and optimize alertness is with the aid of pharmaceuticals. Hypnotic medications may be used to promote daytime sleep among night shift workers with persistent difficulty initiating sleep and adjusting their circadian phase. However, carryover of sedation to the nighttime shift with potential adverse consequences for nighttime performance and safety must be considered. The nonamphetamine wakefulness promoting medications, including modafinil and armodafinil, can enhance alertness during the night shift for SWD. Their use in SWD is studied in clinical trials and is currently approved by the FDA for this indication.

Shift work is unavoidable in our present 24-hour society; therefore, a substantial proportion of the population is at risk for SWD. Cessation of shift work is curative but may not be an option. All shift workers will likely benefit from education about ways to promote circadian adaptation, increase wakefulness, improve sleep hygiene, increase sleep duration, and promote good health practices. Clinical practice guidelines for shift work and SWD are founded on evidence-based medicine.

Dr. Soriano and Dr. Das are with the Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine; The Ohio State University; Columbus, Ohio.

Since the use of oil burning lamps, followed by the invention of the light bulb by Thomas Edison, there has been a steady growth of nocturnal work. With the increasing demand worldwide to sustain our 24-hour society, it has been estimated that nearly 20% of the labor force worldwide involves work shifts outside the traditional 8:00 AM to 5:00 PM workday (Valentina et al. Sleep. 2014;37[3]:545). Leading this trend is the United States (as seen in the Figure). Shift work is even common in occupations that directly affect the health and safety of others, such as transportation and health care.

Shift work can cause a disruption of our circadian sleep-wake pattern and can often lead to sleep deprivation. Shift work disorder (SWD) is established when this misalignment between the timing of the sleep/wake cycle causes sleep disturbance, insomnia, sleepiness, fatigue, and impaired daytime function. The 2008 Sleep in America Poll assessed sleep and the workplace. The poll found that 58% of shift workers (defined as workers who start their job after 6:00 PM but before 6:00 AM) reported less than 6 hours in bed on workdays compared with 13% of nonshift workers. Shift workers worked more hours per week, were more likely to have other sleep disorders, and were more likely to drive drowsy. Recently reported cross-sectional data from the population-based Survey of the Health of Wisconsin (SHOW), collected from 2008 to 2012, showed that shift workers are more commonly men, minorities, and with lower levels of education (Givens et al. Sleep Health. 2015;1:115).

Shift work is more prevalent in blue-collar workers. However, white-collar nocturnal work is increasing as well. According to the US Bureau of Labor Statistics, between 1991 and 1997, there was an 11% increase in the number of white-collar employees working nights compared with only a 6% increase among blue-collar employees (Mcmenamin, Monthly Labor Review. 2007;Dec:3).

Work hours in the United States and elsewhere.

(adapted from Hamermesh et al. 2014. Long work weeks and strange hours. National Bureau of Economic Research.)

A potential health risk

Shift workers and those with SWD may be at greater risk for many health concerns. The SHOW data found shift workers to be more overweight than traditional schedule workers and reported more sleep problems, such as insomnia symptoms, insufficient sleep, and sleepiness. Shift workers have an increased risk of sleep disorders, cardiovascular disorders, obesity, and cancer.

Regarding cardiovascular disorders, shift work has been associated with coronary artery disease, hypertension, and cardiovascular death. The risk of death from heart disease was 19% higher among those who worked rotating night shifts for 6 to 14 years and 23% higher for those who worked rotating night shifts for 15 or more years according to the Nurses’ Health Study (Gu et al. Am J Prev Med. 2015;48[3]:241). While numerous studies have suggested higher prevalence of cardiovascular disease among shift workers, a clear causal pathway has not been established. Possible explanations for the increased cardiovascular disease include circadian stress along with behavioral changes, such as decreased physical activity and dietary changes in night shift workers. Shift work and sleep deprivation can lead to insulin resistance and type 2 diabetes, which can further increase cardiovascular risk. Other theories suggest physiologic stress, such as autonomic dysfunction, cortisol dysregulation affecting inflammation, or endothelial dysfunction.

Shift work has recently been associated with malignancy. Most notably, shift work has been associated with breast cancer. This risk appears to be greatest with prolonged rotating night shift early in one’s career (Schernhammer. Occup Environ Med. 2014;71[1 Suppl]:A121). The relationship between shift work and breast cancer is likely related to the changes in the circadian melatonin levels due to nocturnal exposure to light through multiple pathways (Hill et al. Endocr Relat Cancer. 2015;22[3]:R183). Recent data from the Nurses’ Health Study report a 25% increased risk of lung cancer among women working rotating shifts for more than 15 years compared with those working no night shifts. There is limited and inconsistent evidence for an association between shift work and prostate and colon cancers.

Irregular work hours not only result in physiologic stress but also psychosocial stress. With greater difficulties controlling personal hours, decrease work-life balance, and insufficient recovery sleep, family and social relationships are vulnerable to deterioration. This chronic “social jet lag” is associated with sleep deprivation, absenteeism, and depression.

Working during our circadian-predicted sleep phase can be associated with sleepiness at work. Risk for errors and accidents appear to be higher in shift workers with nearly three-fold increased risk of occupational and commute-to-home accidents compared with day workers (Swanson et al. J Sleep Res. 2011;20[3]:487). There is reported increased risk of motor vehicle accidents in health-care workers and police and commercial drivers working nights compared with those that do not work night shifts (Wright et al. Sleep Med Rev. 2013;17[1]:41). Risk of vehicular, aviation, and industrial accidents are highest at night, especially in the early morning hours.

What can we do?

As health-care providers treating sleep disorders, we commonly encounter shift workers and SWD. It is our responsibility to identify these at-risk patients and provide early intervention. Optimally, shift workers should attempt to sleep immediately after their night shift. Promoting good sleep hygiene is essential; restricting caffeine and alcohol consumption prior to bedtime, and turning off phones and other electronic devices during daytime sleep prevents disturbance. It is also important to educate family members regarding the need for protected sleep time for shift workers.

Administration of melatonin prior to daytime sleep may help to phase-shift the sleep period and provide a soporific effect. However, the data have not definitively supported improvements in sleep with morning (AM) melatonin use. Appropriately timed light exposure is critical to adaptation to a nocturnal schedule. Use of bright light during the first half of the night shift and increasing outside light exposure in the evening prior to starting one’s shift can phase delay the circadian pacemaker. Likewise, avoiding bright light on the ride home and in the morning is necessary to fully adapt to a night schedule. This can be done with use of dark sunglasses on the ride home. The scheduled daytime sleep period should be done in a dark room.

Ideally, those working night shifts should maintain their nocturnal schedule even on days off to allow them to stay in circadian phase. However, this is often not practical with family and personal responsibilities. Adjuncts to optimize workplace alertness and safety may be used. Caffeine use may enhance alertness during the night shift. Napping in the afternoon before starting a night shift and for brief periods throughout the night can be effective in improving alertness. More workplaces are providing sleep rooms to facilitate naps during work hours.

A final option to promote sleep and optimize alertness is with the aid of pharmaceuticals. Hypnotic medications may be used to promote daytime sleep among night shift workers with persistent difficulty initiating sleep and adjusting their circadian phase. However, carryover of sedation to the nighttime shift with potential adverse consequences for nighttime performance and safety must be considered. The nonamphetamine wakefulness promoting medications, including modafinil and armodafinil, can enhance alertness during the night shift for SWD. Their use in SWD is studied in clinical trials and is currently approved by the FDA for this indication.

Shift work is unavoidable in our present 24-hour society; therefore, a substantial proportion of the population is at risk for SWD. Cessation of shift work is curative but may not be an option. All shift workers will likely benefit from education about ways to promote circadian adaptation, increase wakefulness, improve sleep hygiene, increase sleep duration, and promote good health practices. Clinical practice guidelines for shift work and SWD are founded on evidence-based medicine.

Dr. Soriano and Dr. Das are with the Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine; The Ohio State University; Columbus, Ohio.