Sleep disorders in night and shift workers

Sleep disorders in night and shift workers


  • 1 Human behavior and biological rhythms
  • 2 Changes of work shifts or “shift-work”
  • 3 Why does night work generate so much fatigue?
  • 4 Suprachiasmatic nucleus (NSQ) and circadian rhythms
  • 5 What are the possible biological impacts on night workers?
  • 6 Possible cognitive-behavioral manifestations in night workers
  • 7 10 strategies to adapt circadian clock in night workers

Human behavior and biological rhythms

The human being is designed to work during the day and rest at night, sleep is one of the basic human needs; while we sleep, it decreases: blood pressure, heart rate and other functions "lower their rhythm" so that our wonderful brain is responsible for "coordinating the maintenance and repair" of our body, that is, important physiological functions are performed during sleep. Biological rhythms have been fundamental to our evolutionary development, while circadian rhythms are what is called "body clock", determines our sleep patterns.

The society in constant movement requires people who work while many sleep at night, in developed countries, it is estimated that approximately 20% of the population works in night shifts. This is the case of hospital staff, as well as other health units, supervisors, surveillance teams, carriers, auditors and telephone operators, among others. The wakefulness patterns constantly altered in night workers and with turnicity are linked to significant morbidity which is why it increasingly attracts the attention of health professionals.

The nocturnality is an aggravating factor for health in itselfWhen we add a work shift to it, it has more negative consequences on people's quality of life. In addition to the fact that there are greater occupational and health risks. Tiredness, chronic fatigue and drowsiness increase accident risk in night workers and with constant shift changes, being 2 times higher to day workers; while the aging process can be 5 times greater than that of a person who works during the day. It should be taken into account that many night workers perform other tasks during the day that prevents them from getting adequate rest.

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Changes of work shifts or “shift-work”

The circadian rhythm is essential to determine sleep patterns, to define every 24 hours when we sleep and when we wake up, it is programmed through the light-dark cycle. In people who have rotating work shifts, the sleep-wake pattern can also be altered, so they usually present circadian rhythm disorders, associated with the change of assigned shift, especially in workers whose night role is included in this role, this happens because when their biological clock was just getting used to the established shift they change it, forcing the organism of the person to perform another time alterations in sleep-wake patterns, preventing the body from being restored at night. They may have symptoms similar to those of the circadian dysrhythmia or "jet-lag": daytime fatigue, drowsiness, insomnia and gastrointestinal problems.

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Frequent changes in sleep continuity

  1. Shorter duration of sleep.
  2. Drowsiness at times when they should be "functional" to work, study or perform daily activities.
  3. Insomnia.
  4. Reduction of alertness during waking periods.
  5. Circadian dysrhythmia or "jet-lag".
  6. Alterations in the sleep-wake pattern:
  • Delayed sleep pattern.
  • Advanced sleep pattern.
  1. Circadian sleep-wake rhythm disorders associated with work shifts.

How is the disorder evaluated?

There are some valuation tools to determine the duration and impact of sleep disorders such as:

  1. Epswort Sleepiness Scale (ESE).
  2. Insomnia Severity Index (ISI, Insomnia Severity Index).
  3. Pittsburgh Sleep Quality Scale (PSQI).
  4. Multiple Sleep Latency Test (TLMS).
  5. Vigil Maintenance Test (TMV).
  6. Registration of actigraphy with polysomnography.

Why does night work generate so much fatigue?

During the day and night the activity patterns of brain waves change, night workers often experience fatigue, which can become chronic. Because the work is done in a period of deactivation. When a person is exposed to light, even if it is artificial before 5 in the morning, the body can experience it as if instead of a "morning awakening" it was a "sunset", because its "biological clock" is out of adjustment.

Why does the body of human beings when they sleep during the day not have a rest and sleep just as restful, physiologically speaking? When night workers want to rest they finally find a series of stimuli in the environment that does not allow them to have such a restful sleep.

What are some daytime stimuli that make it difficult for the night worker to rest? The state of circadian "alert" is stronger during the day, so we tend to pay more attention to certain environmental stimuli such as light, aromas, noise: telephone, mobiles, traffic ... All these, as well as the sounds coming from home and Outside of a world in constant motion, important factors affect daytime sleep.

Suprachiasmatic nucleus (NSQ) and circadian rhythms

In the medial hypothalamus, we can find the suprachiasmatic nucleus (NSQ), which primarily regulates circadian rhythms, promotes the production of melatonin through the pineal gland,  our biological clock adjusts, through the light information received by the retina. The light emitted by compact fluorescent lamps (CFL), is highly harmful, due to ultraviolet C radiation with short wavelength, which can cause deterioration in proteins, the DNA (Deoxyribonucleic Acid) of the eyes, the skin, affects the electromagnetic field of the person and also generates greater photosensitivity.

Night workers can be affected in different aspects. First, about sleep-wake patterns, but many of those who suffer from sleep disorders due to night work or turnicity often develop social problemsSometimes there are unavoidable social commitments, including family members, the divorce rate is approximately 50% higher in people with night shifts. Often, they don't get enough rest, so they can have significant changes in their mood, a common one is the depression, as well as disorders of anxiety.

What are the possible biological impacts on night workers?

Possible impacts on the health of night workers
Physiological manifestations
GastrointestinalCardiocirculatoryOncological Disorders
Due to hypothalamic alterations, because your body constantly has to deal with the imposed work rhythms and its own biological rhythms,

present a 3.9 times greater risk of manifesting stomach ulcers. Other frequent ones are:

  • Alterations in appetite.
  • Gastritis.
  • Colitis.
  • Constipation.
  • Dyspepsia.
  • Esophageal reflux.
  • Flatulence.
  • Duodenal ulcers.
Higher incidence in the consumption of food with large amounts of unfavorable carbohydrates and low nutritional value.

There is a greater inclination to the consumption of tobacco, coffee, other energy drinks, alcohol and other substances that eventually generate physical and mental dependence.

Have 2 times more possibilities of developing cardiovascular diseases. The most commons are:

  • Overweight.
  • Headaches
  • Hypertension (HT).
  • Coronary heart disease and arrhythmias, associated with an increase in the production of noradrelin among night workers.
In night workers, it has been found that the pineal gland at night interrupts the production of N-acetyl-5-methoxytryptamine, better known as melatonin because of exposure to artificial light, modifying the metabolic state and also the body PH which could increase the risk of suffering breast cancer

In 2007, the IARC (International Agency for Research on Cancer) considered turnicity as probably carcinogenic in humans, classifying it within Group 2A.

Shift work has been associated with the non-Hodgking lymphoma (NHL), endometrial tumors and prostate cancer.

“What rhythm does your life follow? Lack of chronic sleep tends to increase the risk of diabetes, cardiovascular disease and obesity ”

People who have sleep disorder due to night work or turnicity have a five times greater risk of metabolic syndrome (MS), the WHO (World Health Organization) tells us that it is enough to classify it as MS, when a subject simultaneously states:

  • Insulin Resistance
  • High density lipoprotein levels below recommended.
  • Alterations in blood glucose levels.
  • Hypertension (HT).
  • Overweight, obesity or prominent abdomen.
  • Triglyceride figures above normal.

Possible cognitive-behavioral manifestations in night workers

People with work syndrome in unusual shifts suffer significant changes in neurophysiological measurements of attention and memory" Gumenyuk et al., 2014.

Night workers have a 2.5 times greater risk of presenting psychiatric conditions, there has also been a higher prevalence of suicidal ideas, as well as in the use, abuse and dependence on: hypnotics, antidepressants, anxiolytics, analgesics and gastric protectors. The cognitive-behavioral problems that occur most frequently among night workers are:

  • Emotional affective disorder or emotional affective disorder (SAD) Seasonal Affective Disorder)
  • Occupational burnout syndrome.
  • Asthenia.
  • Irritability and lack of emotional regulation.
  • Difficulty making decisions.
  • Emotional lability or sudden mood swings
  • Memory and attention problems.
  • Neurasthenia.

10 strategies to adapt circadian clock in night workers

If you work in night shifts, try to prepare yourself to perform your work properly, try to do your work with good spirits, anyway you are already putting your heart in it to forced marches! Your body requires extra energy and vital resources; When resting during the day, there is not much chance of repairing harmful effects that lack of nighttime sleep causes.

Have you paid attention to the biological rhythm you emit? Remember that biological rhythms make us adapt as organisms to certain conditions, they depend on everyday phenomena that affect us such as temperature, climate and the amount of light. You can follow these strategies to have a better daytime rest:

  1. Make yourself a check-up at least once a year and follow medical recommendations.
  2. make a nap daytime, less than 30 minutes before starting work night shift.
  3. Food hygiene: No matter how much sleep you have, do not suppress any food and try to make them quality foods, although it is more likely that in night shifts, you feel like it or you are facilitated by the consumption of foods with high caloric content and low nutritional value, remember that your body needs quality food to maintain your health, so even if your brain yells at you: Sleep! At the end of your turn, try to nourish your body before with easily digestible foods, not eating well and sleeping could easily become a habit, the health consequences would be very harmful.
  4. Keep your body well hydrous.
  5. Perform physical activity Suggested by health professionals at least 5 times a week for 30 minutes, if it can be outdoors and sunbathing, it is better.
  6. Cognitive-Behavioral Therapy (CBT): to have more rest, you can learn progressive muscle relaxation, visualization and breathing exercises, among others.
  7. Stimulus control techniques: use earplugs, comfortable eye mask, heavy curtains or blinds, maintain a pleasant and adequate climate to rest, establish specific times, places and routines for sleeping.
  8. Avoid the consumption of energy drinks, alcohol, tobacco and other drugs to keep you "awake".
  9. Stay away from bright screens at least one hour before bedtime: the light they emit and visual stimuli contradict internal circadian physiology.
    • Reduce or limit the use of social networks before going to rest.
    • Turn off your mobile or disable notifications. Keep it at least 3 meters away from your body while you sleep.

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In most countries, not all the risks that workers have night shifts represent are taken into account, but you can do it yourself. If you suspect you may have a sleep disorder, start wearing a dream diary, where you record the hours in which you sleep and wake up, it can be of great help for your diagnosis and treatment with a health professional, who is recommended to attend as soon as possible if you have problems to rest.


Bibliographic references

  • Harrison Y, Horne J. (2000). The impact of lack of sleep in decision making: a review. Journal of Experimental Psychology: Applied. 6: 236-249.
  • American Psychiatric Association (2014). Guide to the DSM-5 Criteria. Washington, D.C./London, England. Publisher: Panamericana.