Shift Work Disorder

Shift Work Disorder is a circadian rhythm sleep disorder characterized by insomnia and excessive sleepiness affecting people whose work hours overlap with the typical sleep period. Shift work has been linked to increased risks for developing numerous serious health problems. Further, sleep during the day is shorter and less consolidated than night-time sleep, which has direct effect on cognition and emotions. This may be because of the disruption of the circadian system, which regulates the release of different chemicals in the body, most importantly the hormone melatonin.

The term "shift work" includes both long-term night shifts and work schedules in which employees change or rotate shifts. Shift workers may increase the probability of developing health problems such as:

diabetes
obesity
cancer
depression
dementia
fatigue
stress
sexual dysfunction
cardiovascular disease
heart attacks
metabolic disorders
digestive disorders
musculoskeletal disorders
reproductive disorders
menstrual irregularities
cluster headaches

Shift work also creates a greater risk for human error at work, disrupts cognitive ability and flexibility and impairs attention, motivation, decision making, speech, vigilance, and overall performance. It can also contribute to strain in marital, family, and personal relationships. In addition, shift work is known to cause certain social issues that adversely affect well-being and happiness.

Shift work is known to cause certain social issues that adversely affect well-being and happiness.

SHIFT WORK SLEEP DISORDER TIED TO CIRCADIAN RHYTHMS

A chronic misalignment of the circadian system is a major characteristic of night shift work. Ending work in the early hours of morning, most night shift workers are exposed to extremely bright lights that signal the start of the day, while they need to prepare to sleep. Because nearly all of night shift workers never adjust to their nocturnal work schedule due to bright light exposure, sleep and circadian rhythms disruption is inevitable. This in turn leads to an increased risk of serious health problems and diseases. Further, day sleep is usually shorter and of lesser quality which has direct effect on cognition and emotions.

The health consequences of shift work may depend on chronotype, that is, being a day person or a night person, and what shift a worker is assigned to. When individual chronotype is opposite of shift timing (day person working night shift), there is a greater risk of circadian rhythms disruption. One of the most alarming risks of shift work is the link between night shift workers and and higher risk of cancer. Studies have shown that female night shift workers have a statistically significant, 48%, increased risk of breast cancer. This may be due to alterations in circadian rhythm. Melatonin is a known tumor suppressor and late shifts may disrupt its production. While day-active individuals produce melatonin at night, night shift workers' production of melatonin is suppressed at night due to light exposure.

The WHO's International Agency for Research on Cancer listed "shift work that involves circadian disruption" as a probable carcinogen. Other studies have demonstrated significant links between melatonin deficiency and risks for colon and prostate cancer. Shift Work Sleep Disorder (SWSD) Shift work sleep disorder is a circadian rhythm, sleep disorder characterized by insomnia, excessive sleepiness, or both. People working rotating shifts are more vulnerable than others.

The primary symptoms of shift work sleep disorder are insomnia and excessive sleepiness associated with working and sleeping at non-standard times. Total daily sleep time is usually shortened and sleep quality is less in those who work night shifts compared to those who work day shifts. The boundary between a "normal response" to the rigors of shift work and a diagnosable disorder is blurred.

The symptoms of shift work disorder include (from the National Sleep Foundation):

Excessive sleepiness when you need to be awake, alert, and productive.
Insomnia, or the inability to sleep when you need to. This can mean trouble falling asleep, or waking up before you’ve slept sufficiently.
Sleep that feels unrefreshing or insufficient
Difficulty concentrating
Lack of energy
Irritability or depression
Difficulty with personal relationships

Most people who work shifts will experience some difficulty with these symptoms—for example waking up after fewer than 7-9 hours of sleep or feeling drowsy while on the job. For people with shift work disorder, however, this is an ongoing problem that continually causes symptoms and starts to interfere with work or family life.

A chronic misalignment of the circadian system is a major characteristic of night shift work.

Melatonin is a known tumor suppressor and late shifts may disrupt its production.

Shift work sleep disorder is a circadian rhythm, sleep disorder characterized by insomnia, excessive sleepiness, or both.

HOW CIRCADIAN EYEWEAR CAN HELP SHIFT WORK (SLEEP) DISORDER

Classified as a medical device, Circadian Eyewear is a virtual darkness device which works by eliminating the blue light wavelengths from reaching the retina to trigger natural secretion of melatonin. The light-dark cycle is the most important environmental time cue for entraining circadian rhythms especially for shift workers. To maximize a delay of the body clock, bright blue light exposure should occur in the evening or first part of the night shift. In the morning bright/blue light should be avoided.

Wearing Circadian Eyewear during the morning commute home from work can improve circadian adaptation by blocking the bright/blue light from the eyes to simulate darkness while allowing vision. Granted that one cannot drive with our blue blocking glasses at any time. In about half an hour of wearing the glasses the secretion of melatonin starts to help relaxation and boost the immune system. Circadian Eyewear works as a melatonin treatment and may increase sleep length during both day for night shift workers. Melatonin has been shown to accelerate the adaptation of the circadian system to a nighttime work schedule and benefit daytime sleep in an additional direct sleep promoting mechanism.

To maximize melatonin production during night shifts, Circadian Eyewear can be worn while doing tasks which do not require operating any machines or vehicles. Night shift workers can benefit from a nap before starting a night shift, but it should not be lasting more than 20–30 minutes. Brief naps of 10 to 30 minutes are preferred to avoid sleep inertia, a groggy feeling after awakening that can impair performance.

Circadian Eyewear Collection
Circadian Eyewear

Melatonin has been shown to accelerate the adaptation of the circadian system to a nighttime work schedule.

RESEARCH REGARDING SHIFT WORK DISORDER TIED TO CIRCADIAN RHYTHMS

Research From PubMed

Wearing blue-blockers in the morning could improve sleep of workers on a permanent night schedule: a pilot study.

Circadian phase, sleepiness, and light exposure assessment in night workers with and without shift work disorder

Circadian Rhythms of Melatonin, Cortisol, and Clock Gene Expression During Simulated Night Shift Work

Glucocorticoids entrain molecular clock components in human peripheral cells

Natural Light Exposure, Sleep and Depression among Day Workers and Shift workers at Arctic and Equatorial Latitudes

Night Shift Work, Light at Night, and Risk of Breast Cancer

Does Current Scientific Evidence Support a Link Between Light at Night and Breast Cancer Among Female Night-Shift Nurses?

Shift work: health, performance and safety problems, traditional countermeasures, and innovative management strategies to reduce circadian misalignment

Research Sources