You’ve been hanging out for a break, getting through the busy last weeks of work or class. You’re finally ready to relax. And then tiredness descends, you feel the tickle in your throat, and you realise you’re getting sick.

Why does this always seem to happen just in time for a holiday or the weekend?

Some call this the let-down effect or leisure sickness.

But is it real? While you may hear about leisure sickness online and anecdotally, studies on this phenomenon are very limited and often not well designed.

So let’s take a look at the evidence – and what you can do to stay healthy.

What the evidence shows

Leisure sickness is a term coined by Dutch researchers in a 2002 study. It refers to people who are seldom ill during the working week but get sick relatively often on weekends or holidays.

The researchers surveyed 1,893 people and found roughly 3% reported leisure sickness. Symptoms typically included headaches, tiredness, colds and flu, muscle pain and nausea. People were more likely to develop infections on vacation rather than weekends, and symptoms were most common during the first week of their holiday.

However, this research relied on people’s recall, and memory can be unreliable. The definition of leisure sickness was also vague. For example, one person’s idea of “seldom” and “relatively often” may differ from another’s.

Another 2014 study investigated “let-down headaches” by asking 22 participants who regularly experienced migraines to keep a diary of their stress levels and migraine onset.

It might seem counter-intuitive, but reducing stress seemed to trigger the migraine. When they recorded a reduction in stress on one day, they typically developed a migraine within the next 24 hours. If work was the stressor, this could mean a pattern of migraines on their days off.

Some evidence suggests strokes are also more common on weekends than weekdays in some groups. There is no clear cause, but the study authors suggested strokes could be triggered by lifestyle changes on weekends.

So, what’s going on?

The lack of quality research on leisure sickness means we don’t fully understand its potential causes. But there are some theories.

People often travel during vacations, and sit in enclosed, crowded spaces such as planes, increasing their exposure to germs. Travel to distant locations can also expose us to strains of germs we’re not immune to.

On holidays we may also drink more alcohol, which can reduce immune function. And we may be pushing our body to do things we don’t normally do, putting stress on it.

Another theory is that being busy at work makes us distracted and less likely to pay attention to symptoms. On leave, symptoms such as muscle pain or a headache may become more obvious – and we can’t blame it on work. So we may notice sickness more.

But isn’t relaxing good for your health?

There is a complicated relationship between stress and the immune system.

Stress activates the sympathetic nervous system and makes our bodies release hormones such as adrenaline and cortisol.

Chronic stress can mean our cortisol levels are sustained at high levels. Over time, this reduces how well our immune cells respond to infection, so we are more likely to get sick if we come into contact with viruses or bacteria.

But in the short term, both adrenaline and cortisol can actually enhance how well some parts of the immune system work. This means acute stress can temporarily improve our resistance to infection, which is why we may feel busy and stressed but not fall sick. Cortisol’s anti-inflammatory properties can also relieve pain.

But when the acute stress stops – for example, when we finally get a chance to rest – there may be a sudden transition. We no longer benefit from the temporary immune boost or cortisol’s pain relief. So this is when we might fall sick, and feel symptoms such as headaches and muscle pain.

How can I avoid getting sick?

There’s still a lot we don’t understand about how or why leisure sickness might happen. But we know staying active, getting enough sleep and eating a healthy, balanced diet – even when you’re busy – can help boost your immune system.

One Finnish study examined more than 4,000 public employees who were physically inactive. It found those who took up regular exercise, particularly vigorous exercise, were less likely to take sick leave than those who remained inactive.

Given the link between chronic stress and multiple chronic diseases, it is also sensible to manage your workplace-related stress.

There is good evidence that meditation, mindfulness and relaxation techniques can help reduce stress.

There are also steps you can take to reduce the risk of respiratory infections on vacation, so you get to enjoy the whole holiday. Consider keeping up to date with flu and COVID boosters, and taking other precautions, such as wearing an N95 mask on planes and in airports.

Thea van de Mortel, Professor Emerita, Nursing, School of Nursing and Midwifery, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This time of year, most fridges are stocked up with food and drinks to share with family and friends. Let’s not make ourselves and our guests sick by getting things wrong when preparing and serving food.

As the weather warms up, so does the environment for micro-organisms in foods, potentially allowing them to multiply faster to hazardous levels. So put the drinks on ice and keep the fridge for the food.

But what are some of those food safety myths we’ve long come to believe that aren’t actually true?

Myth 1: if you’ve defrosted frozen meat or chicken you can’t refreeze it

From a safety point of view, it is fine to refreeze defrosted meat or chicken or any frozen food as long as it was defrosted in a fridge running at 5°C or below. Some quality may be lost by defrosting then refreezing foods as the cells break down a little and the food can become slightly watery.

Another option is to cook the defrosted food and then divide into small portions and refreeze once it has stopped steaming. Steam in a closed container leads to condensation, which can result in pools of water forming. This, combined with the nutrients in the food, creates the perfect environment for microbial growth. So it’s always best to wait about 30 minutes before refrigerating or freezing hot food.

Plan ahead so food can be defrosted in the fridge, especially with large items such as a frozen turkey or roll of meat. If left on the bench, the external surface could be at room temperature and micro-organisms could be growing rapidly while the centre of the piece is still frozen!

Myth 2: Wash meat before you prepare and/or cook it

It is not a good idea to wash meats and poultry when preparing for cooking. Splashing water that might contain potentially hazardous bacteria around the kitchen can create more of a hazard if those bacteria are splashed onto ready-to-eat foods or food preparation surfaces.

It is, however, a good idea to wash fruits and vegetables before preparing and serving, especially if they’re grown near or in the ground as they may carry some dirt and therefore micro-organisms.

This applies particularly to foods that will be prepared and eaten without further cooking. Consuming foods raw that traditionally have been eaten cooked or otherwise processed to kill pathogenic micro-organisms (potentially deadly to humans) might increase the risk of food poisoning.

Fruit, salad, vegetables and other ready-to-eat foods should be prepared separately, away from raw meat, chicken, seafood and other foods that need cooking.

Myth 3: Hot food should be left out to cool completely before putting it in the fridge

It’s not OK to leave perishable food out for an extended time or overnight before putting it in the fridge.

Micro-organisms can grow rapidly in food at temperatures between 5° and 60°C. Temperature control is the simplest and most effective way of controlling the growth of bacteria. Perishable food should spend as little time as possible in the 5-60°C danger zone. If food is left in the danger zone, be aware it is potentially unsafe to eat.

Hot leftovers, and any other leftovers for that matter, should go into the fridge once they have stopped steaming to reduce condensation, within about 30 minutes.

Large portions of hot food will cool faster if broken down into smaller amounts in shallow containers. It is possible that hot food such as stews or soup left in a bulky container, say a two-litre mixing bowl (versus a shallow tray), in the fridge can take nearly 24 hours to cool to the safe zone of less than 5°C.

Myth 4: If it smells OK, then it’s OK to eat

This is definitely not always true. Spoilage bacteria, yeasts and moulds are the usual culprits for making food smell off or go slimy and these may not make you sick, although it is always advisable not to consume spoiled food.

Pathogenic bacteria can grow in food and not cause any obvious changes to the food, so the best option is to inhibit pathogen growth by refrigerating foods.

Myth 5: Oil preserves food so it can be left at room temperature

Adding oil to foods will not necessarily kill bugs lurking in your food. The opposite is true for many products in oil if anaerobic micro-organisms, such as Clostridium botulinum (botulism), are present in the food. A lack of oxygen provides perfect conditions for their growth.

Outbreaks of botulism arising from consumption of vegetables in oil – including garlic, olives, mushrooms, beans and hot peppers – have mostly been attributed to the products not being properly prepared.

Vegetables in oil can be made safely. In 1991, Australian regulations stipulated that this class of product (vegetables in oil) can be safely made if the pH (a measure of acid) is less than 4.6. Foods with a pH below 4.6 do not in general support the growth of food-poisoning bacteria including botulism.

So keep food out of the danger zone to reduce your guests’ risk of getting food poisoning this summer. Check out other food safety tips and resources from CSIRO and the Food Safety Information Council, including testing your food safety knowledge.

Cathy Moir, Team leader, Microbial and chemical sciences, Food microbiologist and food safety specialist, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.