Common Sleep Disorders Increase Risk of Motor Vehicle Crashes and Adverse Health Outcomes in Firefighters
ABSTRACT
Study Objectives:
Heart attacks and motor vehicle crashes are the leading causes of death in US firefighters. Given that sleep disorders are an independent risk factor for both of these, we examined the prevalence of common sleep disorders in a national sample of firefighters and their association with adverse health and safety outcomes.
Methods:
Firefighters (n = 6,933) from 66 US fire departments were assessed for common sleep disorders using validated screening tools, as available. Firefighters were also surveyed about health and safety, and documentation was collected for reported motor vehicle crashes.
Results:
A total of 37.2% of firefighters screened positive for any sleep disorder including obstructive sleep apnea (OSA), 28.4%; insomnia, 6.0%; shift work disorder, 9.1%; and restless legs syndrome, 3.4%. Compared with those who did not screen positive, firefighters who screened positive for a sleep disorder were more likely to report a motor vehicle crash (adjusted odds ratio 2.00, 95% CI 1.29–3.12, p = 0.0021) and were more likely to self-report falling asleep while driving (2.41, 2.06–2.82, p < 0.0001). Firefighters who screened positive for a sleep disorder were more likely to report having cardiovascular disease (2.37, 1.54–3.66, p < 0.0001), diabetes (1.91, 1.31–2.81, p = 0.0009), depression (3.10, 2.49–3.85, p < 0.0001), and anxiety (3.81, 2.87–5.05, p < 0.0001), and to report poorer health status (p < 0.0001) than those who did not screen positive. Adverse health and safety associations persisted when OSA and non-OSA sleep disorders were examined separately.
Conclusions:
Sleep disorders are prevalent in firefighters and are associated with increased risk of adverse health and safety outcomes. Future research is needed to assess the efficacy of occupational sleep disorders prevention, screening, and treatment programs in fire departments to reduce these safety and health risks.
Citation:
Barger LK, Rajaratnam SM, Wang W, O'Brien CS, Sullivan JP, Qadri S, Lockley SW, Czeisler CA, Harvard Work Hours, Health and Safety Group. Common sleep disorders increase risk of motor vehicle crashes and adverse health outcomes in firefighters. J Clin Sleep Med 2015;11(3):233–240.
INTRODUCTION
Sixty-one percent of firefighter on-duty fatalities are caused by heart attacks or motor vehicle crashes.1 Heart attacks are the leading cause of death in both career and volunteer firefighters.1 Motor vehicle crashes are the second leading cause of death in volunteer firefighters and rank third among career firefighters.1 In the general population, road crashes cause an estimated 20–50 million injuries worldwide annually, costing an estimated 518 billion US dollars.2 Twenty percent of serious injuries occurring in road crashes are due to driver sleepiness.3 Moreover, adults who report sleeping six hours or less per day or who snore are more likely to report falling asleep while driving4 Even though more than half of firefighters report sleep disturbances,5 to date, the contribution of sleep deficiency to motor vehicle crashes and health has not been studied in firefighters.
Sleep deficiency in other safety-sensitive occupations is associated with significant safety risks.6–8 Police officers, another class of first responders, at risk of a sleep disorder reported more than 50% increased risk of falling asleep while driving and more than 20% increase in occupational injuries.9 The estimated cost of firefighter injuries in the United States is $3.70 to $11.73 billion each year.10
BRIEF SUMMARY
Current Knowledge/Study Rationale: Heart attacks and motor vehicle crashes are the leading causes of death in US firefighters. We examined whether high risk of a sleep disorder was associated with motor vehicle crashes, cardiovascular disease, and other adverse mental and physical health outcomes in a nationwide cohort of firefighters.
Study Impact: Sleep disorders were found to be highly prevalent in firefighters, and were associated with substantially increased risk of motor vehicle crashes and cardiometabolic diseases. This study provides the rationale for further research evaluating the effectiveness of occupational sleep disorders management programs to identify individuals who are vulnerable to adverse safety and health consequences.
Firefighters most commonly work 24-hour extended-duration shifts.11 Occupations that require night, rotating, or extended duration shifts show increased prevalence of cardiometabolic and mental health disorders.12 Chronic sleep restriction, circadian rhythm misalignment, and sleep disorders (particularly obstructive sleep apnea), all of which occur commonly in shiftworkers, are thought to contribute to these adverse health outcomes.13
In a cross-sectional study, we examined whether high risk of a sleep disorder was associated with motor vehicle crashes, cardiovascular disease, and other adverse mental and physical health and safety outcomes in a nationwide cohort of firefighters.
METHODS
We contacted the 3,511 largest fire departments in the US (based on number of stations) by mail, which resulted in 117 semi-structured telephone interviews with fire department representatives. Based on specific criteria (e.g., previous experience implementing similar programs, other research commitments, adequate health insurance coverage, level of management interest, and the ability to meet technical requirements), 66 fire departments were selected to participate in a sleep health education and sleep disorders screening program. The characteristics of participating fire departments are shown in Table 1. Demographics of firefighters studied are described in Table 2.
 Table 1 Descriptions of 66 participating fire departments. |
 Table 2 Self-reported participant characteristics. |
The workplace-based fatigue risk management program consisted of an educational program delivered in-person by the research team, by a department trainer who was trained by the research team or via an online program and a screening for common sleep disorders. The educational program contained information on healthy sleep, circadian rhythms, caffeine, napping, and other fatigue countermeasures, and included video testimonials from firefighters previously treated for sleep disorders. The education program was deemed mandatory by management in the majority (60.6%) of fire departments, but completion of the screening survey was voluntary.
In order to verify that participants were firefighters employed in partner departments, we compared names, email addresses and/or employee numbers of participants with employee rosters provided by participating fire departments.
The sleep disorders screening questionnaire used validated, self-report screening tools for identifying the risk of obstructive sleep apnea (OSA) (Berlin Questionnaire; sensitivity 0.86, specificity 0.77),14 moderate to severe insomnia (Athens Insomnia Scale; sensitivity 0.93, specificity 0.85),15 and restless legs syndrome (Restless Legs Syndrome Epidemiology, Symptoms and Treatment questionnaire; sensitivity 0.82, specificity 0.90).16 The Berlin Questionnaire was further validated in another group of first responders.9 For shift work disorder (SWD), we used a previously employed screening tool.9 Although not validated, the SWD screening tool was based on The International Classification of Sleep Disorders, 2nd Edition (ICSD-2) diagnostic criteria,17 assessing excessive sleepiness and insomnia components during both overnight work and on vacation/days off/day-work schedule. To be deemed positive for SWD, a firefighter had to report symptoms of insomnia and excessive sleepiness during overnight work but not during the other conditions.
Questions on health and safety were also included in the confidential survey. Participants reported current health status (poor to excellent); previous diagnoses of sleep and other medical disorders (diabetes, cardiovascular disease, gastrointestinal disorder, depression, anxiety); and likelihood of falling asleep while driving, among other health and safety outcomes, including motor vehicle crashes, near crashes (i.e., near-miss motor vehicle accidents or crashes [narrowly avoided property damage or bodily harm] in which you were driving) and injuries that occurred in the past month.
We documented reported motor vehicle crashes by soliciting police reports or detailed descriptions for crashes that were reported to us, using methods previously validated in a similar survey of resident physicians.7
Motor vehicle crashes were deemed the primary safety outcome, and cardiovascular disease, diabetes, and depression were deemed the primary physical and mental health outcomes, respectively. Multiple logistic regression models were used for cross-sectional analysis of the associations among sleep disorder screening outcomes and adverse health and safety outcomes. We adjusted for age, gender, BMI, cigarette smoking, and alcohol consumption. We tested these covariates individually and included only those that were significant (p < 0.10) in the initial models. We then applied a backward elimination method to remove those that were not significant in the final model. Only significant variables (p < 0.05) remained in the final model. Unadjusted and adjusted odds ratios (AOR) with 95% confidence intervals (CI) are reported. Statistical analyses were conducted using SAS for Windows (ver. 9.2, SAS Institute Inc., Cary, NC). A p value < 0.05 was considered statistically significant for the primary outcomes of interest.
RESULTS
Of the total number of firefighters in the 66 fire departments available to participate in the study (18,040), 11,836 participated in the educational program (65.6% participation rate). Of those, 6,933 were verified firefighters who participated in the survey portion of the study (58.6% cooperation rate) (Figure 1). Less than 1% of the cohort identified themselves as volunteer firefighters.
† Based on information collected from ∼10% of participating fire departments, we determined that 97% of firefighters were actively available in the departments at the time of the study.
The demographics of the participants were comparable to national statistics, with women and Hispanics slightly oversampled (5.9% women vs. 3.4% women firefighters nationally; 10.4% Hispanic vs. 8.8% firefighters nationally), and African Americans were slightly underrepresented (3.9% in the survey vs. 7.5% firefighters nationally).18 In the cohort, 50.4% of the firefighters were overweight and 29.3% were obese, compared to 34.1% and 32.2%, respectively, in the US general adult population.19
Nearly all fire departments (97.0%) employed extended duration work shifts ≥ 24 h; twenty percent (19.7%) of departments scheduled firefighters to shifts ≥ 48 hours (Table 1). Mean work hours were 255.9 ± 72.4 per month (approximately 64 h/week, including regular hours, overtime hours, and hours working a second job [reported by 33.7% of participants]; Table 2).
Of participating firefighters, 37.2% screened positive for at least one sleep disorder. OSA was most prevalent, with 28.9% screening positive, followed by SWD (9.1% of those reporting working night shifts [n = 5,771]), and then insomnia (6.1%) and restless leg syndrome (3.4%; Table 3). Most firefighters screening positive reported not having a current diagnosis of the disorder; 80.9% for OSA, 80.3% for insomnia, 98.0% for SWD, and 76.6% for restless legs syndrome.
 Table 3 Sleep disorder screening outcomes for all participants (n = 6,933). |
Ninety-four firefighters reported one or more motor vehicle crashes in the prior month (Table 4); 85% of motor vehicle crashes were documented with police reports or detailed descriptions and, 48% (47/97) occurred at work or during commutes. Those firefighters who screened positive for a sleep disorder were significantly more likely to report a motor vehicle crash (AOR 2.00, 95% CI 1.29–3.12, p = 0.0021; Table 4). Near crashes were also elevated in those screening positive for a sleep disorder (AOR 2.49, 95% CI 2.13–2.91, p < 0.0001; Table 4). Firefighters who screened positive for a sleep disorder were more likely to report falling asleep while driving (AOR 2.41, 95% CI 2.06–2.82, p < 0.0001).
 Table 4 Self-reported safety outcomes, comorbidities and adverse health outcomes associated with positive sleep disorder screening result. |
Positive screening for a sleep disorder was also associated with adverse health outcomes. Those screening positive for a sleep disorder were at significantly greater risk of cardiovascular disease (AOR 2.37, 95% CI 1.54–3.66, p < 0.0001), diabetes (AOR 1.91, 95% CI 1.31–2.81, p = 0.0009), depression (AOR 3.10, 95% CI 2.49–3.85, p < 0.0001), and anxiety (AOR 3.81, 95% CI 2.87–5.05, p < 0.0001; Table 4). Firefighters screening positive for a sleep disorder were more likely to rate their health status more poorly (Table 4). Variables included in the final models used to examine associations between adverse safety and health outcomes and positive sleep disorder screening are shown in Table 5.
 Table 5 Variables included in the models used to examine associations between adverse safety and health outcomes and positive sleep disorder screening. |
When the most prevalent sleep disorder, OSA, and the other three sleep disorders combined, were analyzed separately, all associations with adverse health and safety outcomes remained significant (see Tables S1–S4, supplemental material). In exploratory analysis to examine the potential role of sleep medication in these associations, we analyzed motor vehicle crash risk in firefighters who reported never or nearly never taking sleep-promoting medications in the past month. Unmedicated firefighters who screened positive for restless legs syndrome or insomnia showed a trend towards increased risk of reporting more motor vehicle crashes than those who did not screen positive (9 [2.3%] vs. 64 [1.3%] OR = 1.85 [0.02–3.75] p = 0.0867).
DISCUSSION
More than 80% of firefighters who screened positive for a common sleep disorder were undiagnosed and untreated. Fire-fighters who screened positive for a common sleep disorder had twice the odds of having had a motor vehicle crash in the prior month as compared to those with a negative screening, consistent with the two- to three-fold increased motor vehicle crash risk among patients with excessive daytime sleepiness and individual sleep disorders in the general population.3,20–24 Indeed our study found significant associations between sleep disorder screening and motor vehicle crash risk when examining separately OSA and non-OSA sleep disorders (restless legs syndrome, insomnia, and SWD). We also found that firefighters who screened at risk of any one of the four sleep disorders were at more than 2-fold risk of having been diagnosed with cardiovascular disease or diabetes and more than 3-fold risk of having been diagnosed with depression or anxiety. Our findings demonstrate the impact of common sleep disorders on firefighter health and safety, including, for the first time, the two leading causes of death among firefighters.1 Moreover, these results demonstrate the effectiveness of a workplace screening program in identifying those at risk.
Twenty percent of firefighters who screened positive for a common sleep disorder reported falling asleep while driving at least once per month, suggesting that sleep-related attentional failures are highly prevalent in this group. This is 4.9 times the rate of falling asleep while driving in the general population, and 3.7 times the rate of a falling asleep while driving among snorers in the general population.4 The prevalence of attentional failures while driving in firefighters is also higher than that reported by police officers who screened positive for a sleep disorder (14.4%)9 and first-year medical residents working five or more extended duration shifts (≥ 24 h) per month (12.6%).7
Increased rates of motor vehicle crashes on the commute from work were associated with extended duration work shifts in our previous study of first year medical residents.7 In this firefighter population, nearly all of whom (93%) worked extended shifts, those who screened positive for a common sleep disorder had almost twice the rate of motor vehicle crashes than those who did not screen positive. Our findings are consistent with a previous study showing that individuals with sleep apnea are more vulnerable to the effects of sleep loss on performance.25
The physical health of firefighters was negatively affected by the risk of any sleep disorder. The odds of reporting a current diagnosis of cardiovascular disease or diabetes were 2.4 and 1.9 times higher, respectively, in those who screened positive for a common sleep disorder than those who did not screen positive, even when adjusted for age, gender, BMI, cigarette smoking, and alcohol consumption. According to self-reported height and weight (calculated BMI), the majority of firefighters were overweight (50.4%) or obese (29.3%), an added risk factor for diabetes and cardiovascular disease.
Hypertension is another risk factor for cardiovascular disease that is associated with sleep deficiency.26–28 OSA, the most prevalent sleep disorder in firefighters, is an independent risk factor for hypertension and increases the incidence of stroke.29–32 Tanigawa and colleagues reported that OSA patients were particularly likely to be hypertensive if they were shift workers over 40 years old compared to younger workers.33 Further, shift work has been shown to aggravate the severity of OSA, with a higher apnea-hypopnea index during diurnal sleep after nighttime work shifts and may exacerbate the adverse health outcomes.34
Soteriades and colleagues reported that on-duty cardiovascular disease events occurred almost exclusively among vulnerable firefighters with underlying cardiovascular disease.35 The risk of death from cardiovascular disease was higher in emergency firefighter duties as compared to non-emergency duties.36 Therefore, it was recommended that all fire departments have entry-level and periodic medical evaluations.35 The inclusion of sleep disorders screening into these evaluations may help to identify susceptible firefighters at risk of cardiovascular disease and diabetes.
In our analysis, we adjusted for BMI and other potential confounders to examine independent contribution of common sleep disorders. The adjusted odds ratios support the premise that the sleep deficiency (reduced sleep duration and/or reduced sleep quality) and/or potentially intermittent hypoxia in OSA, the most prevalent sleep disorder in this firefighter cohort, contribute to diabetes.37–39 Indeed, laboratory protocols demonstrate the impact of sleep restriction40 and circadian mis-alignment,41,42 inherent in 24-hour shifts, and the combined impact of these43 on glucose regulation, a marker of diabetes risk. When combined with chronic sleep restriction, prior exposure to circadian disruption has an adverse effect on metabolism, compromising insulin sensitivity and impairing the pancreatic response to a meal.43 Additionally, in epidemiological studies, chronic sleep deficiency and poor sleep quality have been shown to be associated with type 2 diabetes.44,45
In our study, 529 firefighters reported a current diagnosis of depression and/or anxiety (9% depression and/or anxiety; 6% depression; 4% anxiety). Although this is consistent with estimates in the general population,46,47 our study showed a greater than 3-fold increase in the odds of the diagnosis for those who screened positive for a common sleep disorder. Similarly, in a smaller sample of firefighters from one department, depressive symptoms were significantly correlated with sleep deprivation.48 Depression adversely impacts productively and safety; for example, depressed resident physicians made significantly more medication errors compared to those who were not depressed.49 Sleep disorders treatment programs may alleviate the risk of developing depression in those with insomnia and the depressive symptoms in those with OSA.50,51
Circadian misalignment associated with shift work may increase shift workers' risk of depression.52 There is a well-established interrelationship between depression and insomnia,50 and emerging evidence suggests an association between depression and OSA.53–55 Sound mental health is an often-overlooked but critical component of occupational health and productivity, particularly given the high cost of mood disorders on work performance.56
Untreated sleep disorders are an economic burden, reduce productivity at work, and adversely impact social relationships.57–59 Thus, screening should be an initial step in evaluation and treatment programs for sleep disorders. Firefighters who screened positive in this study were referred to a website that provided information on local accredited sleep disorders clinics where further evaluation, diagnosis and treatment, if necessary, could be obtained. These types of programs should be part of any occupational comprehensive fatigue risk management system and/or included in employee wellness programs that aim to reduce chronic disease and improve mental health.
Limitations
The study was limited to departments that had the resources to devote to participation in the healthy sleep education and screening program. Volunteer fire departments, which tend to be small with minimal resources60 were underrepresented in this study. These results can therefore only be generalized to the 300,000 career firefighters in the U.S. We screened for only four sleep disorders, but they are common sleep disorders that are most likely to occur in firefighters. The screening tool for SWD was not validated. This study was cross sectional and outcomes were assessed by self-report. Our primary safety outcome, motor vehicle crashes, was verified by documentation in 85% of the cases as in our previous studies.7 BMI is a major component for determining OSA risk. Although we did not confirm BMI with anthropometric measures in this study, our previous study of police officers showed a high correlation (R = 0.912, p < 0.001) of self-reported height and weight with anthropometric measures. The percentage of overweight and obese firefighters in this study (79.9%) was similar to that previously reported by Poston and colleagues (79.5%), who studied BMI objectively and found firefighters were more likely to be obese when assessed by objective body fat measures.61 Finally, since nearly all of the participating firefighters worked extended duration work shifts, we did not have adequate power to evaluate the impact of extended duration work shifts on firefighter health and safety.
Although our study was not designed to examine the associations between sleep-promoting medication use and motor vehicle crash risk, we observed a trend for the relationship between sleep disorders screening results and motor vehicle crash risk to persist after firefighters reporting taking sleep medications were removed from the analysis. We suggest that this issue should be examined further in future studies given the relationship between sleep medication use and neurobehavioral impairment.62
CONCLUSION
Common sleep disorders were found to be highly prevalent in firefighters, and were associated with substantially increased risk of motor vehicle crashes and cardiometabolic diseases. Occupational sleep disorders screening programs can identify individuals who are vulnerable to adverse safety and health consequences, including those that are leading causes of death in firefighters. This study provides the rationale for further research evaluating the effectiveness of occupational sleep disorders management programs on disease risk, mental health, and safety outcomes.
DISCLOSURE STATEMENT
This work was supported by FEMA Assistance for Firefighters Grants EMW-2007-FP-02197 and EMW-2008-FP-02566. The contents of this manuscript are solely the responsibility of the authors and do not necessarily represent the official views of the Federal Emergency Management Agency or the Assistance to Firefighters Grant Program. The federal sponsor did not have a role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript. Dr. Barger has received research support through her institution from Cephalon, and has participated in speaking engagements for Vital Issues in Medicine and the National Sleep Foundation. She has consulted for San Jose State University Foundation and Alertness Solutions. Dr. Rajaratnam, through his institution, has consulted to Vanda Pharmaceuticals, Philips Respironics, EdanSafe, National Transport Commission, Rail, Bus and Train Union, Australian Workers' Union, Tontine Group, Meda Consumer Healthcare, and has through his institution received research grants and/or unrestricted educational grants from Vanda Pharmaceuticals, Philips Respironics, and Cephalon, and reimbursements for conference travel expenses from Vanda Pharmaceuticals. His institution has received equipment donations or other support from Optalert, Compumedics, Philips Lighting and Tyco Healthcare. He has also served as an expert witness and/or consultant to shift work organizations. Dr. Lock-ley has received two investigator-initiated research grants from the ResMed Foundation and an unrestricted equipment gift from ResMed Inc. Dr. Lockley has received consulting fees from American Family, Apollo Lighting, Blackrock, Brigham and Women's Hospital, Cowen & Co, Fidelity, Frankel Group, Impax Laboratories, Kearney Venture Partners, Lazard Capital Markets, Naturebright, Perceptive Advisors, Polar Capital, ResearchWorks Inc., Thomas Jefferson University, Warwick Medical School, and Wyle Integrated Science and Engineering and Wyvern Funds. He holds is currently consulting for Headwaters, PlanLED and Wyle Integrated Science and Engineering; has received unrestricted equipment gifts from Bioilluminations LLC, Bionetics Corporation, and Philips Lighting; an unrestricted monetary gift to support research from Swinburne University of Technology, Australia; has received a fellowship gift from Optalert, Pty, Melbourne, Australia; has equity in iSLEEP, Pty, Melbourne, Australia; has received advance author payment and royalties from Oxford University Press; has received payment for editing a textbook section from Elsevier; has received honoraria for written articles by Servier Inc., AMO Inc., the National Sleep Foundation, and the Wall Street Journal; has received honoraria plus travel, accommodation, or meals for invited seminars, conference presentations or teaching from 2nd International Symposium on the Design of Artificial Environments, American Society for Photobiology, Bassett Research Institute, Brookline Adult Education, Brown University; Emergency Social Services Association Conference, Harvard University (CME), I Slept Great/Euforma, LLC, International Graduate School of Neuroscience, Japan National Institute of Occupational Safety and Health, Lightfair, MediCom Worldwide, Inc (CME), North East Sleep Society, Notre Dame University, Takeda Pharmaceuticals North America, Thomas Jefferson University, University of Vermont College of Medicine, and Velux; has received travel and accommodation support (no honoraria) for invited seminars, conference presentations or teaching from 8th International Conference on Managing Fatigue, 14th Annual Tennessee Perfusion Conference, American Academy of Sleep Medicine, Apollo Lighting, Bar Harbor Chamber of Commerce, Canadian Sleep Society, Committee of Interns and Residents, Coney Island Hospital, Connecticut Business & Industry Association Health and Safety Conference, Emergency Services Steering Committee, FASEB, Ferrari, Harvard University, Illinois Coalition for Responsible Outdoor Lighting, Lighting Science Group Corp, Massachusetts General Hospital, National Research Council Canada, New England College of Occupational and Environmental Medicine, New York Academy of Sciences, Ontario Association of Fire Chiefs, Oxford University, Philips Lighting, Rio Tinto, Sleep HealthCenters, UMass Memorial, University of Manchester, University of Montreal, University of Texas Medical Branch, University of Tsukuba, Vanda Pharmaceuticals, Warwick Medical School, Woolcock Institute of Medical Research, and Wyle Integrated Science and Engineering (NASA). Dr. Lockley has completed investigator-initiated research grants from Alcon Inc, and Apollo Lighting and has ongoing investigator-initiated research grants from Biological Illuminations LLC, Philips Lighting, Respironics Inc, and Vanda Pharmaceuticals; has service agreements with Rio Tinto Iron Ore and Vanda Pharmaceuticals; and has two completed and one ongoing sponsor-initiated research contracts with Vanda Pharmaceuticals. Dr. Lockley holds a process patent for the use of short-wavelength light for resetting the human circadian pacemaker and improving alertness and performance which is assigned to the Brigham and Women's Hospital per Hospital policy. He has also received minor revenue from a patent on the use of short-wavelength light which is assigned to the University of Surrey. Dr. Lockley has also served as a paid expert on behalf of five public bodies and one union on arbitrations related to sleep, circadian rhythms and work hours. Dr. Czeisler has received consulting fees from or served as a paid member of scientific advisory boards for: Bose Corporation; Boston Celtics; Boston Red Sox; CITGO, Inc.; Cleveland Browns; Colombia River Bar Pilots; Merck; Novartis; Purdue Pharma LP; Quest Diagnostics, Inc.; Teva Pharmaceuticals Industries Ltd.; Valero, Inc.; Vanda Pharmaceuticals, Inc. Dr. Czeisler owns an equity interest in Lifetrac, Inc.; Somnus Therapeutics, Inc.; and Vanda Pharmaceuticals, Inc., and received royalties from McGraw Hill, Penguin Press/Houghton Mifflin Harcourt, and Philips Respironics, Inc. Dr. Czeisler has also received grants and research support from Cephalon, Inc.; National Football League Charities; Philips Respironics. The Harvard Medical School Division of Sleep Medicine (HMS/ DSM), which Dr. Czeisler directs, has received unrestricted research and educational gifts and endowment funds from Boehringer Ingelheim Pharmaceuticals, Inc.; Cephalon, Inc.; Gerald McGinnis; Jazz Pharmaceuticals; Merck & Co., Inc.; Peter C. Farrell, PhD; ResMed; and Respironics, Inc. The HMS/DSM has received gifts from many outside organizations and individuals including Committee for Interns and Residents; Gerald McGinnis; Jazz Pharmaceuticals; Jordan's Furniture; NeuroScience; Novartis Consumer Health; Purdue Pharma; ResMed Foundation; Safe-way; Transcept Pharmaceuticals; United Healthcare; Vanda Pharmaceuticals, Inc.; Weight Watchers International; and YMCA of the USA. The HMS/DSM Sleep and Health Education Program has received Educational Grant funding from Cephalon, Inc.; Takeda Pharmaceuticals; Sanofi-Aventis, Inc.; Sepracor, Inc.; San Francisco Bar Pilots; and Sysco. Dr. Czeisler is the incumbent of an endowed professorship provided to Harvard University by Cephalon, Inc. and holds a number of process patents in the field of sleep/circadian rhythms (e.g., photic resetting of the human circadian pacemaker). Since 1985, Dr. Czeisler has also served as an expert on various legal and technical cases related to sleep and/or circadian rhythms including matters involving Bombardier, Inc.; Delta Airlines; FedEx; Greyhound; Michael Jackson's mother and children; Purdue Pharma, L.P.; United Parcel Service (UPS); and the United States of America. The other authors have indicated no financial conflicts of interest.
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