Shift Work: Is it Killing You? And Survival Manual Timothy Daum MD Spectrum Health Grand Rapids “Working at night must be regarded as an inherently unnatural act” Principles and Practice of Sleep Medicine Third Edition • Optimal sleep and wakefulness requires proper alignment between our schedule and our underlying internal clock. • Humans are the only animal that routinely go against their internal clocks. • Fooling Mother Nature is not easily accomplished and has its price. Background • We live and work in a 24/7 world • Up to a quarter of workers spend a significant part of their work hours on nonday shifts • Higher percentage of health care workers involved in shift work We are Diurnal Animals • Humans are inherently active during the day • We have an intrinsic circadian (about a day) pacemaker that affects almost all biologic rhythms. – – – – Temperature regulation Hormone secretion Cognitive function Sleep-Wake rhythms • This circadian rhythm is kept on target by exposure to sunlight. • Designed to improve chances of survival Circadian Rhythm Accidents vs. Time of Day Shift Work and Circadian Rhythms • It is difficult to perform at peak capacity when our internal clock is telling us it is time for sleep. • Coversely, It is difficult to sleep when our internal clock and external factors (light) is telling us we should be awake and active. Shift Work and Circadian Rhythms • If we traveled 12 time zones we would completely adjust our circadian rhythms over time – We adjust about 1 time zone per day • With shift work we never completely shift our circadian rhythm – Lack of correlation between light and sleep/wake cycle Circadian Adjustment in Young Adults Circadian Factors • Even if we adjust our internal circadian rhythm over the course of a week, most people revert to the normal schedule over weekends requiring we restart our adjustment every week. Sleep Diary of a Night Shift Worker Shift Work - Factors Shift Work Factors • Circadian Factors – Sleep is disrupted as we try to sleep during daylight hours – We are trying to work during the time our body is in a “down” phase – Our circadian rhythms are out of phase Shift Work Factors • Sleep Factors – Shift workers get 5-7 hours less sleep per week than those on day shifts • REM sleep mainly affected – Most shift workers are in a state of chronic sleep deprivation • Performance and safety issues Shift Work Factors • Domestic Factors – The majority of the world remains on a daylight schedule • Parenting obligations • Phone calls • Noise levels – Shift work is a significant strain on relationships • Increased risk of divorce by 57% Shift Work Disorder • International Classification of Sleep Disorders, 2nd Edition • Insomnia or excessive sleepiness related to a recurring work shift that overlaps the usual sleep time. – 32% of night workers meet diagnostic criteria. – More prevalent with increasing age. Shift Work Disorder: Risk Factors • • • • Older age Women Morning larks Reverse rotating – Evening, Day then Night Health Effects of Shift Work • Cardiovascular morbidity and mortality – Increased risk of MI • Gastrointestinal effects – Dyspepsia – Higher rate of ulcers • Endocrine – Impaired glucose tolerance • Accidents and work performance • Psychiatric – Higher rates of depression – Higher rates of alcohol/substance abuse Shift Work and Cardiovascular Morbidity • Shift work had been associated with: – Higher lipid levels – Increased risk of hypertension – Higher incidence of coronary artery disease • RR 2.0 for 6-10 years of shift work • RR 2.8 for 16-20 years Shift Work and Mortality • Indian Railway Company • Very complete records • Different job types between day and shift workers Increased Risk of Accidents: Sleeping in the Cockpit How to Survive Shift Work • • • • Be a night owl (Delayed sleep phase individual) Avoid daytime light Sleep in a totally dark room Melatonin 1-3 mg before sleep has a weak beneficial effect • Short acting sleeping pills improve sleep with no proven increase in work performance • Provide enough time for sleep • Napping prior to work How to Survive Shift Work • Caffeine has been shown to improve shift-work performance • Modafanil (Provigil) is FDA approved for shift work • Permanent shifts provide more sleep than rotating shifts • Clockwise rotating schedule – Slow rotations (at least 5 days per shift) are probably better than rapidly rotating schedules How to Survive Shift Work • Address other potential causes of sleepiness – – – – OSA Restless Legs Narcolepsy Idiopathic Hypersomnia How to Survive Shift Work • If all else fails: • GO INTO MANAGEMENT!