Night shift – The right diet
Working night shifts disrupts the normal biorhythm and presents the body with particular challenges. Find out here how you can adapt your diet and lifestyle to best compensate for the negative effects of shift work.
Working the night shift poses health risks
In Germany, around 15% of employees work shifts that involve working until late in the evening. Around 5% of these people also work regularly during the night.
With these values, Germany is close to the EU average. The leader in terms of night shifts is Slovakia, with a share of night work of 11% (as of 2021)
Studies show that people who regularly work night shifts may have an increased risk of various diseases, including cardiovascular diseases or cardiovascular risk factors such as atherosclerosis and hypertension ( ), metabolic diseases such as type 2 diabetes (), and even cancer
A healthy diet and lifestyle can help minimize these risks and counteract the negative effects of night shifts.
Nutritional challenges when working night shifts
Eating well when working regular night shifts or shift work in general is a particular challenge. Irregular working hours or a life that goes against your normal biorhythm make it difficult to stick to regular meal times and to ensure you eat a healthy, balanced selection of foods.
Common problems are:
Ready meals, fast food and unhealthy snacks
The tiredness and exhaustion after a night shift encourages an unhealthy diet, as it seems tiring and time-consuming to prepare a healthy meal. Many people therefore prefer to eat ready meals.
The stress and lack of time during a night shift encourage the hasty eating of unhealthy snacks and fast food during working hours.
Emotional eating behavior
Stress, lack of sleep, a disturbed biorhythm and lack of exposure to daylight encourage emotional eating, which further promotes the consumption of unhealthy foods and can lead to weight gain.
Food cravings
Eating irregularly and eating unhealthy foods leads to fluctuating blood sugar levels, causing cravings that often lead to unhealthy food choices.
Lots of caffeine
In order to stay awake, many night workers consume far too much coffee or other caffeinated beverages, which disrupts sleep and regeneration and can lead to dehydration and mineral loss.
Lack of planning
Night and shift work can also affect the balance between work and family life, making it even more difficult to plan and prepare healthy meals.
How night shift work disrupts the day-night rhythm
The human body functions according to an internal clock that is subject to various rhythms. There is the day-night rhythm, a monthly rhythm for women and also an annual rhythm depending on the seasons.
In particular, the day-night rhythm, which is also known as the circadian rhythm, is crucial for controlling numerous biological processes and thus has a significant influence on our health and well-being. This rhythm is thrown out of balance by night shift work.
Daylight plays a key role in controlling the day-night rhythm. However, people who work night shifts sleep during the day and therefore do not get to enjoy daylight, or only to a limited extent.
Blue lights during the day
Natural daylight contains a high proportion of blue light, which stimulates the production of the hormone cortisol in the adrenal cortex in the morning. Cortisol is important for preparing the body for the day. The increase in cortisol levels causes blood pressure and blood sugar levels to rise, among other things. All of this makes you awake and alert.
In addition to the release of cortisol, bright daylight also promotes the production of the neurotransmitter serotonin , which is also known as the happiness hormone. Serotonin has extensive effects in the body, particularly on the psyche. For example, it is said to increase our well-being and reduce the perception of stress. Serotonin is also the starting material for the production of melatonin – the sleep hormone.
Over the course of the day, not only does the proportion of blue light in daylight gradually decrease, but the cortisol level also drops continuously. Instead, the production of melatonin starts in the pineal gland (epiphysis). This hormone makes us tired and allows us to fall asleep. The blue light in the morning, on the other hand, stops the production of melatonin so that the organism can wake up under the influence of cortisol.
To find out how you can increase or regulate your melatonin levels naturally, read our article on Melatonin: Effects and Side Effects .
Red light in the evening
Towards the evening, the proportion of long-wave red light increases and the inhibitory effect of blue light on melatonin production disappears. As the accumulation of melatonin increases, the body prepares for sleep and we feel tired and relaxed. The night shift worker must therefore be fit if his body wants to sleep. Otherwise, he produces less melatonin because the necessary signals are missing (darkness, quiet) and suffers from the consequences of a melatonin deficiency.
Sufficient production of melatonin is important for restful sleep with sufficient deep sleep phases. Deep sleep is a basic requirement for the body’s regeneration processes, such as the repair of damaged DNA, the renewal of cells, the release of growth hormones or the detoxification processes. The activity of the immune system is at its highest during deep sleep.
However, melatonin is not only important for restful sleep, but is also the most important antioxidant in the central nervous system. A lack of melatonin therefore promotes the development of neurodegenerative diseases such as Parkinson’s and Alzheimer’s ( ).
Consequences of a disturbed biorhythm
Factors such as artificial light in the evening and at night ( ), an irregular and unhealthy diet, stress, lack of sleep and excessive consumption of caffeine can disrupt our complexly regulated biorhythm, which can lead to a variety of health problems. The factors mentioned are ubiquitous problems when working the night shift ( ).
Below we present some examples that show how an impaired biological rhythm can affect our health and why it increases the risk of health problems and diseases such as obesity, diabetes, cardiovascular disease, cancer and depression ( ).
Night shift leads to less sleep and poorer sleep quality
Because people who work night shifts sleep during the day, they must go to sleep during the waking phase of a normal circadian rhythm. This makes it difficult to fall asleep, which can significantly shorten the time it takes to sleep. Environmental conditions such as lighting and noise can also further disrupt sleep and prolong the period of wakefulness.
Night shift workers have, on average, 2–4 hours less sleep per night compared to day workers ( 10 ). The quality of sleep is also impaired, with fewer deep sleep phases and fewer REM (rapid eye movement) sleep phases.
Read the red light section above to find out why deep sleep is so important for the body’s regeneration. REM sleep is particularly important for linking memories and newly learned information.
The consequences of poor sleep quality due to night shifts include:
- reduced physical performance,
- a weakened immune system,
- persistent fatigue ( ),
- reduced attention, concentration and ability to react ( ).
In addition to the direct physical damage, chronic sleep deprivation also increases the risk of errors and accidents at work, in traffic, and in everyday life ( ).
Night shift weakens the immune system
Working the night shift can have a significant impact on the immune system. Many processes in the immune system, such as the activity of certain types of immune cells, are influenced by the circadian rhythm. The disruption of the biorhythm therefore also impairs normal immune function and promotes infectious diseases and autoimmune processes ( ).
Studies show that lack of sleep weakens both the innate and the acquired parts of the immune system and also leads to a pro-inflammatory state in the body ( ). This inflammatory state is an important factor in the development of the “diseases of civilization” mentioned above.
Night shift increases cancer risk
Various studies show a connection between an increased risk of cancer and working night shifts. The WHO even lists shift work as a possible cause of cancer ( ).
This connection has been confirmed several times, particularly for colon cancer. Researchers believe that the increased cancer risk can be attributed to artificial lights at night and a variety of genetic and hormonal interactions ( ).
Women who work night shifts also have almost twice the risk of developing breast cancer compared to women who work during the day. This was found, among other things, by a Polish study that evaluated the data of around 1,000 women. Those who developed breast cancer were particularly likely to have worked night shifts ( ).
Night shift increases digestive problems
Night shift workers are particularly prone to digestive problems, such as constipation and diarrhea, flatulence, abdominal pain, heartburn and nausea, as well as irritable bowel syndrome or other serious gastrointestinal diseases ( ).
It is important to know that not only is our day-night rhythm controlled by an internal clock, but that our internal organs, such as the digestive tract, also have their own internal clock, according to which various processes in the respective organ take place.
In an American study ( ), researchers investigated the influence of night shifts on the day-night rhythm and on the internal clock of the digestive system. To do this, they divided 14 subjects into two groups.
The first group worked a simulated day shift for three days and slept between 10 p.m. and 6 a.m. The other group did exactly the opposite: the subjects worked night shifts for three days and were only allowed to sleep between 10 a.m. and 6 p.m. Blood samples were taken regularly and over 100 different parameters were analyzed.
The results showed that the volunteers who worked the night shift not only had their internal biological clock (that is, the main pacemaker in the brain – see next section) shifted by two hours, but that the internal clock of their digestive system was also shifted by up to 12 hours.
Discrepancy between main pacemaker and digestive tract
The main pacemaker of the circadian rhythm is called the suprachiasmatic nucleus. This is a small area in the hypothalamus of the brain that controls the 24-hour cycle and thus our day-night rhythm.
The suprachiasmatic nucleus synchronizes the body’s internal clocks with external signals such as light and darkness by responding to light pulses received through the eyes. In doing so, the master pacemaker regulates the production of melatonin and other hormones that affect the sleep-wake cycle and other important physiological processes.
When working the night shift, there is a discrepancy between the rhythm of the main pacemaker and the internal clock of the gastrointestinal tract. This causes many processes in the digestive system to become unbalanced. These include, for example, the formation and secretion of digestive enzymes and bile or peristalsis (movements of the intestinal wall).
Night shift disrupts normal digestion
During a night shift in particular, the gastrointestinal tract is not prepared to digest food efficiently. Depending on how much and what type of food is consumed, the occurrence of digestive problems is more likely. But it’s not just about eating during the night. Night shift workers generally have an increased risk of digestive problems , no matter when they eat.
In addition to the discrepancy in biological rhythms, other harmful factors include changing meal times, often unhealthy food choices and often hasty, stressed eating during a night shift. In medical professions in particular, there is often little time and there are often no breaks, so employees quickly “stuff” a few snacks in passing and carry on working.
Unhealthy foods with lots of sugar, unhealthy fats and many artificial food additives do the rest to damage the gastrointestinal tract. Other damaging factors for the digestive system include insufficient chewing, a lot of stress and lack of sleep.
Each of the factors mentioned can lead to digestive problems. For people who work night shifts, this means that several serious causes come together.
Disturbed intestinal flora due to night shift work
An important connection as to how digestive problems arise is a disruption of the microbiome. The harmful factors listed lead to a disruption of the composition of the intestinal flora and an increased proliferation of harmful germs ( ). This is an essential mechanism that leads to the development of digestive problems.
As you have seen, there are some factors that you can influence yourself. In the section “How can you counteract the harmful effects of the night shift?” we go into detail about how you can counteract the health effects of the night shift through food choices and meal timing.
Night shift affects metabolism
A disturbed biorhythm also has profound effects on metabolism. The change to night work can affect the release of important hormones such as insulin and leptin, which regulate blood sugar levels and the feeling of hunger. The reduced production of melatonin, the increased amount of oxidative stress in the body ( ) and the disruption of cortisol release play a central role in the disruption of normal metabolic regulation.
Ultimately, this impairment of normal metabolic processes can lead to insulin resistance and increases the risk of obesity , type 2 diabetes and metabolic syndrome
Metabolic syndrome is the combination of impaired glucose metabolism (insulin resistance), altered blood lipid levels (increased triglyceride and cholesterol levels, high LDL cholesterol), high blood pressure and obesity. Insulin resistance refers to a reduced response of cells to insulin, resulting in chronically elevated blood sugar and insulin levels. Insulin resistance often leads to the development of type 2 diabetes.
Numerous studies confirm that night shift workers have increased levels of inflammation, blood lipids and fasting glucose compared to other employees ( 26 ).
A study that analyzed data from nearly 20,000 nurses over a 15-year period found that nurses who worked night shifts had a 58% increased risk of developing diabetes compared to nurses who worked during the day. Those who worked the evening shift also had an increased risk of diabetes, but only by 29%
A study from Switzerland with over 2300 employees compared the influence of day and night work on the risk of developing metabolic syndrome. An increased risk was demonstrated especially for men. An increased amount of visceral fat tissue in men who worked at night was mentioned as an important connection ( ).
Visceral fat tissue is the fat that surrounds the internal organs in the abdominal cavity. An increased amount of visceral fat is particularly bad for health, as this fat tissue is highly hormonally active and, among other things, produces pro-inflammatory messengers and promotes inflammatory processes in the body as well as the development of insulin resistance.
Night shifts increase risk of cardiovascular disease
As presented in the previous section, working the night shift is associated with increased cardiovascular risk factors such as diabetes, obesity, high blood pressure and elevated blood lipid and cholesterol levels.
There are currently few studies on the occurrence of cardiovascular diseases in night shift workers. However, one study shows, for example, an increased risk of coronary heart disease ( 29 ).
More frequent mental illnesses among night shift workers
Circadian rhythm disruption can also increase the risk of depression, anxiety disorders, and addictions ( ). For example, a study of about 800 Chinese employees showed that people who work night shifts have a more than four-fold increased risk of developing depression ( ).
