Can you ever get used to working night shifts?
Last Sunday the Daylight Saving Time ended, and if your reaction was similar to mine, it felt like we plunged right into the darkest time of year. Only a few days earlier, I'd be out and about in broad daylight to get your parcels delivered to you on time, then all of a sudden dusk had set in already.
Maybe your reaction was similar, or if you are someone who rises early, you're happy to see the sun back for a short while when waking up.
Or, perhaps you aren't seeing the sun much at all, because you belong to the almost 20% of people who habitually work at weird hours. Some of you may only work night shifts, while others will have rotating shifts.
For those of you, who may for one reason or another will have to work in shifts soon, we have gathered more background information on how shift work affects your life and how to adapt to it.
Almost everyone has hard time adapting to night shifts, but most people can adapt to it within a few months.
Night shiftsThere are precious few people who really love working the night shift. Those that do, mention how they enjoy a quieter surrounding, not having to worry about traffic jams when commuting back and forth to work. Others work night shifts because it pays better.
Nearly all of them have in common that it is more difficult to sleep at non-traditional hours, resulting in excessive sleepiness during their shifts. Chronic fatigue can impair productivity, safety, health, and quality of life.
A health hazard ?Numerous studies have investigated the possible health consequences of night shift work. It seems health consequences are significant and could represent a huge public health problem in our increasingly 24-hour society. Some of the health problems found to be associated with working nights include the following:
- increased risk for (breast and colorectal) cancer
- increased inflammation
- irregular menstrual cycles and reduced fertility
- increased risk for stroke
- increased risk for bone fractures (wrist and hip)
- impaired glucose sensitivity, leading to increased development of metabolic syndrome and diabetes
- increased blood pressure
- increased risk for cardiovascular disease
- increased risk for mental health disorders, including anxiety and depression
The most alarming risk may very well be the increased risk for cancer, which made the International Agency for Cancer Research come to the following conclusion "shiftwork that involves circadian disruption is probably carcinogenic in humans.
What is circadian disruption?Circadian disruption (also known as chronodisruption) is a disturbance of the circadian organization of human physiology, endocrinology, metabolism, and behavior.
There is a master biological clock in our brain that controls circadian rhythms, such as core body temperature, blood pressure, sleepiness/wakefulness, mental performance, alertness, and secretion of hormones (such as melatonin, cortisol, prolactin, and growth hormone).
The major synchronizers of circadian rhythms are exposure to environmental patterns of light and dark.
These patterns control biological cycles that repeat roughly every 24 hours (the solar day). They allow us to have regular oscillations between sleep and wakefulness, and fasting and eating, that are critical to health.
When our rest-activity cycles match the light-dark cycles of the environment, we are said to be "in phase."
If a person is exposed to inadequate or irregular amounts of light at certain times of the day, circadian rhythm can be disrupted, causing asynchrony between the circadian system and the solar day.
This is believed to be the root of long-term negative health impact of night shift work.
If you doubt that working the night shift seriously disrupts circadian organization, consider this: working a typical night shift schedule creates biological clock stress that is analogous to the jet lag of flying back and forth between several time zones every few days.
It is no coincidence that airline personnel who criss-cross time zones have health consequences similar to those of night-shift workers.
The main cause for chronodisruption is exposure to light at night, when humans are supposed to be sleeping.
The main 'time'-related hormone is melatonin, which is the "messenger of time" that transmits information about environmental light and darkness, obtained from the retina, through the hypothalamus to all tissues of the body.
Melatonin is synthesized and secreted at night, acting as a signal for the length of day and night. Melatonin is also a well-known oncostatic hormone that inhibits tumor growth. Light suppresses melatonin secretion in a dose- (or intensity-) dependent manner. Night sleep normally occurs during the rising phase of melatonin secretion.
If a person tries to sleep during the declining phase of melatonin secretion, sleep can be shorter with more awakenings.
A Good Day's SleepThe other significant health risk comes from the nature of sleep itself when one works at night and sleeps during the day. Fatigue in night-shift workers is the result of the combination of shorter sleep hours and and poorer quality of sleep.
Daytime sleep is more fragmented and less restorative than nighttime sleep. Night workers are not only deprived of more restful sleep, their sleep deprivation is compounded by sleep loss that builds over successive shifts because their sleep times are shorter, often by 1-4 hours, compared with night sleepers.
This results in a cumulative "sleep debt" and feelings of chronic fatigue that can't easily be erased with "catch-up" sleep.
Sleep, fatigue, and safetyAlmost by definition, lack of sleep will result in fatigue and sleepiness. By consequence, many of the worst accidents in history have taken place on the night shift.
The effects of lack of sleep and excess of fatigue are among others :
- slower reaction time
- attention lapses
- less attention to detail
- compromised problem-solving
- impaired psychomotor skills
- reduced coordination
- more errors of omission
Fatigue isn't the only symptom experienced when working the night shift. Irritability, forgetfulness, stress, chills, nausea, and eye strain are other common complaints of night-shift workers that can affect performance or physical and mental well-being.
Research confirms that the ability to perform tasks declines throughout the night shift, especially during the second half of the shift.
The worst performance coincides with the time when body temperature is lowest between 4-6 am, a finding supported by lower levels of perceived alertness during these hours.
Even partial sleep deprivation is associated with an increased likelihood of making an error and a decreased likelihood of catching someone else's error. Rotating shifts, especially more rapidly rotating schedules, are associated with increased error rates. The risk for making an error or being involved in an incident increases with of the number of successive night shifts. The risk for an incident at work is 6% higher on the second night shift, 17% higher on the third, and 36% higher on the fourth.
Extreme drowsiness while driving or cycling home is another major danger. The effects of sleep deprivation on mental alertness are similar to those seen in people who have drunk too much alcohol.
Due to the difference between individuals, it is hard to predict how much sleep someone requires to make him or her "safe." Nor is there any consensus on the extent of impairment resulting from a given amount of sleep loss.
Are you a lark, a night owl or a humming bird?People often describe themselves as being either a "morning person" or a "night person." This characteristic is also called the 'chronotype' which gets lovingly labeled as being a 'lark' or an 'owl'.
If you prefer to rise early, feel most alert and perform best in the morning, and go to bed early, you are an early chronotype, or lark. If you prefer to sleep late, work best later in the day, and stay up well past midnight, you are a late chronotype, or owl. Those who are somewhere in between (which is most of the population) are hummingbirds. Experts say about 1 in 10 people are larks, 2 in 10 are owls, and the rest are hummingbirds.
Generally night owls have an easier time to adapt to working at night.
However, even "owls" don't stay up all night like some species of owls. It is simply not natural for humans to do so, and human "owls" have difficulty resetting their internal clocks if compelled to stay awake all night.
Should I nap or not during work?Naps are often recommended, and frequently practiced, as an effective strategy for staving off sleepiness on the night shift.
It seems to make sense to nap, but there's a drawback to napping : both a too long as well as a too short nap can leave you groggy and/or exhausted. It is recommended to take short naps of up to 20 minuhtes.
The other disadvantage that gets mentioned is how it may make it even more difficult to truly adapt to night work and day sleeping.
Whether napping should be a stop-gap measure to combat unanticipated sleepiness or part of a planned sleep-wake strategy to promote sleep health in regular night-shift workers is not currently known. Nor is there much known about the effects of napping at night on subsequent sleep quality, or whether napping regimens can counteract the negative physiologic consequences of working nights in the first place.
While there hasn't been a whole lot of research on sleep schedules with or without naps, there are plenty individuals who have experimented with different sleep schedules.
For those of you , that are interested in the various different sleep schedules and may be looking for ways to be more productive and sleep fewer hours, it is worthwhile to read a very informative article on polyphasic sleep cycles which led to another one 5 years later.
How to adapt to night shiftsThe extent to which human circadian rhythms can adapt to a night shift is not known. Nor is it known whether such adaptation would negate the health consequences of working the night shift.
With respect to adaptation, the best strategy is staying awake at night, and sleeping during the day, even on your days off, if your family obligations allow you to do that.
To get used to this pattern, sleep in a very quiet, very dark room (or use a blindfold).
At work, seek out brightly lit areas. You need bright light exposure, but most indoor lighting is insufficient.
Preferably, don't nap during your shift.
If you can't be strict with an altered sleep/wake schedule, the next best strategy is that of sleeping late before your first night shift, rather than going without sleep.
Suggestions for decrease the negative effects of shift work and diminish fatigue are :
- if you work 8-hour rotating shifts, rotate clockwise (day -> evening -> night)
- avoid rapid rotation, so try not to accept work schedules that have you work different shifts in the same week
- follow a regular sleep schedule regardless of which shift you are working
- use room-darkening or blackout shades in your bedroom
- spend as much time as possible in brightly lit rooms
- wear sunglasses to block blue light when driving home in the morning
- don't schedule appointments or activities during your routine sleeping hours
- after your last night shift, sleep for 4 hours
- avoid caffeine and nicotine before sleeping
- seek exposure to bright light after waking
Many other measures have been assessed for their value in helping workers adapt to shift work, including supplemental melatonin, chemical sleep aids, use of stimulants, and physical exercise.
With the exception of physical exercise, all of these measures have potential drawbacks. However, a regular exercise program can benefit night-shift workers not only by helping them tolerate the night shift but also in reducing the somatic symptoms associated with poor sleep and working nights.