Shift work and headaches: a new perspective

Shift work is far from unusual

Figures from Germany’s Federal Statistical Office for 2023 indicate that around 15% of the country’s workforce works shifts at least occasionally. 9% worked nights between 11 p.m. and 6 a.m. Men have always been slightly more highly represented among shift workers and that is still the case, with 28% working during evening hours, 16% working shifts, and 12% nights. Among women, 23% worked evenings, 13% shifts, and 6% nights. These statistics show that a significant share of the country’s economic activity takes place outside normal working hours.

The body clock

The “body clock”, or circadian rhythm, is our internal timer that regulates sleep, energy, and key bodily functions. This finely tuned system makes sure that day-night changes in our environment influence activity, rest, and sleep. The human circadian rhythm is remarkably consistent and hard to deliberately change. It varies between 23.5 and 25 hours and is adjusted each day by sunlight acting as an external time cue.

The body identifies the time of day through the brightness of sunlight. Melanopsin, a visual pigment in the retina of the eye, plays a key role in this process. Melanopsin perceives changes in light intensity with great precision. These signals are then transmitted via the optic nerve to the brain, where they are processed. In this way, the 24-hour cycle is regulated, and the internal clock is adjusted slightly forward or backward as needed. Certain glands in the brain are also involved in these processes. Over the course of the day, they release different messenger substances, which in turn influence numerous functions and states of the body depending on the time of day. In their complex interaction, all these processes generate the human circadian rhythm, affecting muscle tension, body temperature, hormone levels in the blood, and the sensitivity of our sensory organs and nerve pathways. This circadian rhythm is not unique to humans. The entire animal kingdom, right down to single-celled organisms, responds in the same way to the recurring cycles of its environment.

Shift work disorder: a recognized condition

In this article from early 2022, we described the phenomenon of shift work disorder, a complex condition with physical, emotional, and psychological components. Impaired sleep is the main problem. People with shift work disorder have a total duration of sleep that is considerably shorter than among people who work daytime hours. Persistent tiredness can be the result. Some people develop chronic fatigue syndrome, a state of physical exhaustion combined with impaired mental performance.

Other common problems include gastrointestinal disturbances, which can eventually develop into inflammatory diseases of the digestive tract. Cardiovascular issues also come into the picture. Typical mental health issues associated with shift work disorder include anxiety and depression. Increased irritability, difficulty concentrating, and nervousness may also occur. The burden of suffering is often made worse by family issues and social difficulties, since shift work has a profound impact on family life and social participation.

A Norwegian research group that analyzed 29 different studies on this topic estimated that more than one in four shift workers (26.5%) are affected by this condition. And there’s another significant concern: in 2007, the World Health Organization (WHO) classified permanent night work as “probably carcinogenic”.

Shift work and headaches: new research findings

A new review published in 2024 provides a broad overview of current knowledge on the relationship between shift work and headaches. It evaluated a series of scientific studies involving more than 400,000 participants overall. Taken together, the results show a measurable, statistically significant increase in the risk of headaches and migraines among shift workers, with night work in particular carrying the highest risk.

For migraine, studies with more than 4,500 participants demonstrated that night work clearly increases the likelihood of attacks. The number of night shifts per month seems to be strongly linked to the frequency of migraine attacks. The authors say these associations are clearly demonstrated across all the groups of employees studied. The effect was observed regardless of gender or occupation. One Danish study additionally found that employees working late shifts were at increased risk of debilitating migraine attacks.

Health care workers at special risk

Several studies consistently indicate that nurses and care workers are particularly affected by the risk of headaches resulting from shift work. With respect to migraine, the same gender-related differences were observed as in the general population: women had about twice the risk of migraine headaches compared to their male colleagues. In other words, women in health care therefore suffer more from migraine than men. This seems to apply across the board, whether they are working regular daytime hours or in shifts.

Can the impact be reduced?

If avoiding shift, night, or weekend work is not possible, experts recommend limiting night work to no more than three consecutive night shifts. These should rotate forward, for example: early – early – late – late – night. Afterward, there should be a rest period of at least 24 hours – ideally, two to three days off. For late shifts as well, no more than three in a row should be scheduled. Complete weeks of only late shifts should be avoided whenever possible.

Practical tips for night and shift workers

The latest research confirms the significant impact of shift work on people’s headache burden. The following everyday tips offer practical guidance on how to organize shift work so as to prevent headaches as much as possible.

The central role of sleep

For people who work shifts, irregular sleep patterns are one of the biggest problems. A key tip is to keep the change between sleep and waking times as consistent as possible, particularly when switching from early to late shifts and vice versa. Night shifts are more difficult, but there are strategies that can help here too.

Very bright lighting (such as daylight lamps) during the first half of a night shift can help delay the onset of tiredness. If manageable, short naps of about 30 minutes during the shift can help too. In the second half of a night shift, and in late shifts, caffeine consumption should be avoided and lighting reduced as much as possible. Bright sunlight on the morning journey home should also be avoided. This is because, as darkness fades, the body’s sleep-inducing messenger substance (melatonin) stops being released. The body wakes up, making it harder to fall asleep when the time comes. Experts therefore recommend wearing sunglasses on the way home in bright light. Once home, the bedroom should be as dark as possible to help you fall asleep quickly.

Nutrition

In general, people who work shifts should try to eat regularly despite their changing schedules. For main meals, dishes with lean meat or fish and carbohydrate-rich sides such as potatoes, rice, or vegetables are recommended. Cold meals might consist of a mixed salad and/or wholegrain bread with generous toppings. Staying hydrated is equally important. Two to three liters is the recommended daily fluid intake.

During night shifts, two meals are advisable. If a hot meal is not possible, a cold snack can be paired with a hot cup of tea. A second meal should be eaten about two hours before the end of the shift to maintain concentration and performance. Suitable options would include vegetable soup, unsweetened fruit compote, milk and dairy products, fruit, or a light salad. After a night shift, before going to bed, a small breakfast is recommended. Caution is advised, though, as an overly rich breakfast and caffeinated drinks can make it hard to fall asleep and stay asleep.

Breaks

Anyone working shifts should take short breaks at regular intervals – although that may be difficult in settings such as hospitals. Breaks should ideally be spent outdoors, which improves blood circulation to the brain and enhances your concentration. A particularly useful method is Jacobson’s progressive muscle relaxation, a medically tested and easy-to-learn relaxation technique. By consciously tensing and relaxing different muscle groups, the entire body experiences deep relaxation, making even short breaks more effective. This exercise is available in the Prevent Headache app or here on the website.