Quick version
"Leisure sickness" is a phenomenon where some people get sick when they go on vacation. There are no reliable statistics that confirm that more people get sick during vacations, but several physiological and psychological factors can explain why it feels so common.
Stress affects the immune system in a complex way. In the short term, stress hormones such as adrenaline can strengthen the body's defenses, but in the case of prolonged stress, cortisol takes over and weakens the immune system. When stress suddenly disappears – for example, during vacations – we can therefore become more susceptible to infections.
In addition to physiological mechanisms, psychology plays a role. During stress, we can ignore symptoms such as fatigue and headaches, but once we relax, we start to notice them more. We also remember more clearly the times we got sick during the leave, which can create a feeling that it happens more often than it actually does.
Lifestyle factors such as lack of sleep, poor diet and high workload before the leave can also make us more vulnerable. A Dutch study found that around 3% of the population experience physical discomfort in connection with the transition to leave, especially those with high demands and difficulty switching off from work.
The phenomenon is not a medical diagnosis, but experts say there is evidence that the immune system can be negatively affected during the transition from stress to rest. The best way to reduce the risk is to take care of your health through balanced stress management, sleep and good lifestyle habits.
The phenomenon is sometimes called “vacation sickness” and internationally it has been called “leisure sickness”. Although there is no data that confirms that we statistically get sick more often during vacation, there are several physiological and psychological explanations for why it feels so common. Experts believe that factors linked to stress, the immune system and lifestyle can interact and make us more susceptible to illness when we finally relax.
The impact of stress on the immune system
Prolonged stress is never good and affects the body's defenses, which can increase the risk of infections. Stress hormones such as adrenaline can temporarily mobilize the immune system – for example, by calling out white blood cells (neutrophils) that “eat up” bacteria – which in the short term can actually keep an incipient infection at bay. This means that during a limited period of stress, the risk of getting sick is lower than usual, because the body is on high alert. However, this enhanced defense does not last long. Chronic or long-term stress wears down the body – after a while, the immune system returns to normal despite the stress, and then the short-term protection disappears. In addition, it is well documented that long-term stress actually weakens parts of the immune system, making us more susceptible to infections such as colds.
Cortisol, another important stress hormone, has a dampening effect on immune reactions; during stressful periods, a lot of cortisol is secreted, which can suppress the immune system. In this way, you can "stay healthy" until the stress subsides – but the cost is that you accumulate increased vulnerability that manifests itself later.
When you unwind, the immune system relaxes
Many people find that as soon as they take a break and relax, "the disease catches up". One physiological effect is that if you have been exposed to a virus during an intense period, the stress reaction may have temporarily held back the symptoms. At the same time that the stress decreases and the levels of stress hormones drop, the immune system also relaxes – and then the infection can fully break out.
A similar effect occurs after a long period of stress is over: the immune system can then be temporarily weakened.
Psychological factors such as relaxing and "feeling after" play a role
In addition to the purely biological mechanisms, psychology also plays a role. When we are in the middle of work and stress, the brain prioritizes the feeling of minor ailments – we "don't have time" to feel how we feel. The focus on solving tasks means that many people ignore or suppress symptoms such as fatigue, headaches or the onset of a cold. Once we are free and have the opportunity to let our bodies and minds relax, we suddenly notice the symptoms – our bodies are signaling things we previously pushed aside.
In addition, during vacation, you have more time for yourself, which can make you feel more carefully. Instead of being distracted by work and chores, you have time to register every itchy throat or headache.
Another psychological aspect is memory bias. We particularly notice and remember events that ruin our long-awaited vacations. Being bedridden with the flu during Christmas or getting a fever on the first day of vacation is so frustrating that it is etched in our memory. We therefore tend to remember the times we have been sick on weekends or holidays much more clearly than all the times we have been healthy.
Lifestyle factors during intense periods
Another explanation lies in how we live before the vacation begins. Often, a hectic period at work leads to us neglecting healthy habits. Lack of sleep, poor diet and excessive caffeine consumption are common during high stress. Specialist doctor Erik Lind points out that during stress, many people are careless with food and drink, a relatively common example is that you may live on coffee and skip meals – which depletes the body's reserves. This can mean that the body does not get all the nutrients it needs, and the immune system is kept up "on credit" until the stress eases. When time off comes and you may be exposed to viruses (for example when traveling or socializing), the body has a harder time resisting because it is exhausted and not at its peak physically.
Sleep and recovery also play a big role. During stressful periods, many people sleep too little, which is known to weaken the immune system. If you go straight from an intense work week into vacation mode, without giving your body a chance to gradually unwind, your immune system doesn't have time to recover. Erik Lind describes how our resistance to infections deteriorates when we are not in optimal physical shape. If we suffer from sleep deprivation and elevated cortisol levels due to prolonged stress, our immune system becomes more vulnerable. When we are then exposed to more people and new infections during the holidays, the risk of getting sick increases. In other words, lifestyle factors such as lack of recovery and nutritional intake can exacerbate the negative effects of stress, making us extra susceptible to infections just when we are finally relaxing.
Does “vacation sickness” really exist?
Despite the fact that many people identify with the phenomenon, “vacation sickness” is not an official diagnosis but rather a concept that has arisen from these recurring observations. There are no clear statistics that show that people generally get sicker during vacations - it may well be our experiences and memories that trick us into believing that it is more common than it is. At the same time, there is research and expert opinions that support that it can happen under certain circumstances. A Dutch study from the early 2000s investigated the phenomenon where some individuals experience physical discomfort in connection with going from work to vacation. The researchers found that around 3% of those surveyed reported symptoms such as fatigue, muscle aches, nausea and cold-like symptoms at the start of their leave. Those most affected often had demanding jobs with high performance requirements and difficulties in releasing work-related stress. The study indicated that people with an intense work pace and a strong commitment to their job had a higher tendency to develop this condition, which has come to be called leisure sickness.
Several experts consider the phenomenon credible even though it is not yet fully scientifically proven. Susceptibility to infection is a fact after long-term stress and that the combination of this and psychological factors may be behind the impression that people often get sick when they are on leave.
However, Erik Lind emphasizes that once a virus takes hold, we get sick regardless of whether we happen to be on leave or not. The best thing we can do is take care of our overall health: by living healthily, managing stress appropriately, sleeping well and eating well, we can give our immune system better conditions – both during hectic periods and when we take time off.
