Everyone seems to have a different opinion when it comes to how often towels and bed sheets should be washed. While many people might wonder whether days or weeks is best, in one survey from the United Kingdom, almost half of single men reported not washing their sheets for up to four months at a time.

It’s fairly clear that four months is too long to leave it, but what is the ideal frequency?

Bed linen and towels are quite different and so should be washed at different intervals. While every week or two will generally suffice for sheets, towels are best washed every few days.

Anyway, who doesn’t love the feeling of a fresh set of sheets or the smell of a newly laundered towel?

Why you should wash towels more often

When you dry yourself, you deposit thousands of skin cells and millions of microbes onto the towel. And because you use your towel to dry yourself after a shower or bath, your towel is regularly damp.

You also deposit a hefty amount of dead skin, microbes, sweat and oils onto your sheets every night. But unless you’re a prolific night sweater, your bedding doesn’t get wet after a night’s sleep.

Towels are also made of a thicker material than sheets and therefore tend to stay damp for longer.

So what is it about the dampness that causes a problem? Wet towels are a breeding ground for bacteria and moulds. Moulds especially love damp environments. Although mould won’t necessarily be visible (you would need significant growth to be able to see it) this can lead to an unpleasant smell.

As well as odours, exposure to these microbes in your towels and sheets can cause asthma, allergic skin irritations, or other skin infections.

So what’s the ideal frequency?

For bedding, it really depends on factors such as whether you have a bath or shower just before going to bed, or if you fall into bed after a long, sweaty day and have your shower in the morning. You will need to wash your sheets more regularly in the latter case. As a rule of thumb, once a week or every two weeks should be fine.

Towels should ideally be washed more regularly – perhaps every few days – while your facecloth should be cleaned after every use. Because it gets completely wet, it will be wet for a longer time, and retain more skin cells and microbes.

Wash your towels at a high temperature (for example, 65°C) as that will kill many microbes. If you are conscious of saving energy, you can use a lower temperature and add a cup of vinegar to the wash. The vinegar will kill microbes and prevent bad smells from developing.

Clean your washing machine regularly and dry the fold in the rubber after every wash, as this is another place microbes like to grow.

Smelly towels

What if you regularly wash your towels, but they still smell bad? One of the reasons for this pong could be that you’ve left them in the washing machine too long after the wash. Especially if it was a warm wash cycle, the time they’re warm and damp will allow microbes to happily grow. Under lab conditions the number of these bacteria can double every 30 minutes.

It’s important to hang your towel out to dry after use and not to leave towels in the washing machine after the cycle has finished. If possible, hang your towels and bedding out in the sun. That will dry them quickly and thoroughly and will foster that lovely fresh, clean cotton smell. Using a dryer is a good alternative if the weather is bad, but outdoors in the sun is always better if possible.

Also, even if your towel is going to be washed, don’t throw a wet towel into the laundry basket, as the damp, dirty towel will be an ideal place for microbes to breed. By the time you get to doing your washing, the towel and the other laundry around it may have acquired a bad smell. And it can be difficult to get your towels smelling fresh again.

What about ‘self-cleaning’ sheets and towels?

Some companies sell “quick-dry” towels or “self-cleaning” towels and bedding. Quick-dry towels are made from synthetic materials that are weaved in a way to allow them to dry quickly. This would help prevent the growth of microbes and the bad smells that develop when towels are damp for long periods of time.

But the notion of self-cleaning products is more complicated. Most of these products contain nanosilver or copper, antibacterial metals that kill micro-organisms. The antibacterial compounds will stop the growth of bacteria and can be useful to limit smells and reduce the frequency with which you need to clean your sheets and towels.

However, they’re not going to remove dirt like oils, skin flakes and sweat. So as much as I would love the idea of sheets and towels that clean themselves, that’s not exactly what happens.

Also, excessive use of antimicrobials such as nanosilver can lead to microbes becoming resistant to them.

Rietie Venter, Associate professor, Clinical and Health Sciences, University of South Australia

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

We all want to eat healthily, especially as we reset our health goals at the start of a new year. But sometimes these plans are sabotaged by powerful cravings for sweet, salty or carb-heavy foods.

So why do you crave these foods when you’re trying to improve your diet or lose weight? And what can you do about it?

There are many reasons for craving specific foods, but let’s focus on four common ones:

1. Blood sugar crashes

Sugar is a key energy source for all animals, and its taste is one of the most basic sensory experiences. Even without specific sweet taste receptors on the tongue, a strong preference for sugar can develop, indicating a mechanism beyond taste alone.

Neurons responding to sugar are activated when sugar is delivered to the gut. This can increase appetite and make you want to consume more. Giving into cravings also drives an appetite for more sugar.

In the long term, research suggests a high-sugar diet can affect mood, digestion and inflammation in the gut.

While there’s a lot of variation between individuals, regularly eating sugary and high-carb foods can lead to rapid spikes and crashes in blood sugar levels. When your blood sugar drops, your body can respond by craving quick sources of energy, often in the form of sugar and carbs because these deliver the fastest, most easily accessible form of energy.

2. Drops in dopamine and serotonin

Certain neurotransmitters, such as dopamine, are involved in the reward and pleasure centres of the brain. Eating sugary and carb-rich foods can trigger the release of dopamine, creating a pleasurable experience and reinforcing the craving.

Serotonin, the feel-good hormone, suppresses appetite. Natural changes in serotonin can influence daily fluctuations in mood, energy levels and attention. It’s also associated with eating more carb-rich snacks in the afternoon.

Low carb diets may reduce serotonin and lower mood. However, a recent systematic review suggests little association between these diets and risk for anxiety and depression.

Compared to men, women tend to crave more carb rich foods. Feeling irritable, tired, depressed or experiencing carb cravings are part of premenstrual symptoms and could be linked to reduced serotonin levels.

3. Loss of fluids and drops in blood sugar and salt

Sometimes our bodies crave the things they’re missing, such as hydration or even salt. A low-carb diet, for example, depletes insulin levels, decreasing sodium and water retention.

Very low-carb diets, like ketogenic diets, induce “ketosis”, a metabolic state where the body switches to using fat as its primary energy source, moving away from the usual dependence on carbohydrates.

Ketosis is often associated with increased urine production, further contributing to potential fluid loss, electrolyte imbalances and salt cravings.

4. High levels of stress or emotional turmoil

Stress, boredom and emotional turmoil can lead to cravings for comfort foods. This is because stress-related hormones can impact our appetite, satiety (feeling full) and food preferences.

The stress hormone cortisol, in particular, can drive cravings for sweet comfort foods.

A 2001 study of 59 premenopausal women subjected to stress revealed that the stress led to higher calorie consumption.

A more recent study found chronic stress, when paired with high-calorie diet, increases food intake and a preference for sweet foods. This shows the importance of a healthy diet during stress to prevent weight gain.

What can you do about cravings?

Here are four tips to curb cravings:

1) don’t cut out whole food groups. Aim for a well-balanced diet and make sure you include:

• sufficient protein in your meals to help you feel full and reduce the urge to snack on sugary and carb-rich foods. Older adults should aim for 20–40g protein per meal with a particular focus on breakfast and lunch and an overall daily protein intake of at least 0.8g per kg of body weight for muscle health
• fibre-rich foods, such as vegetables and whole grains. These make you feel full and stabilise your blood sugar levels. Examples include broccoli, quinoa, brown rice, oats, beans, lentils and bran cereals. Substitute refined carbs high in sugar like processed snack bars, soft drink or baked goods for more complex ones like whole grain bread or wholewheat muffins, or nut and seed bars or energy bites made with chia seeds and oats

2) manage your stress levels. Practise stress-reduction techniques like meditation, deep breathing, or yoga to manage emotional triggers for cravings. Practising mindful eating, by eating slowly and tuning into bodily sensations, can also reduce daily calorie intake and curb cravings and stress-driven eating

3) get enough sleep. Aim for seven to eight hours of quality sleep per night, with a minimum of seven hours. Lack of sleep can disrupt hormones that regulate hunger and cravings

4) control your portions. If you decide to indulge in a treat, control your portion size to avoid overindulging.

Overcoming cravings for sugar, salt and carbs when trying to eat healthily or lose weight is undoubtedly a formidable challenge. Remember, it’s a journey, and setbacks may occur. Be patient with yourself – your success is not defined by occasional cravings but by your ability to manage and overcome them.

Hayley O’Neill, Assistant Professor, Faculty of Health Sciences and Medicine, Bond University

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

Our brain is an extremely complex and delicate organ. Our body fiercely protects it by holding onto things that help it and keeping harmful things out, such as bugs that can cause infection and toxins.

It does that though a protective layer called the blood-brain barrier. Here’s how it works, and what it means for drug design.

First, let’s look at the circulatory system

Adults have roughly 30 trillion cells in their body. Every cell needs a variety of nutrients and oxygen, and they produce waste, which needs to be taken away.

Our circulatory system provides this service, delivering nutrients and removing waste.

Where the circulatory system meets your cells, it branches down to tiny tubes called capillaries. These tiny tubes, about one-tenth the width of a human hair, are also made of cells.

But in most capillaries, there are some special features (known as fenestrations) that allow relatively free exchange of nutrients and waste between the blood and the cells of your tissues.

It’s kind of like pizza delivery

One way to think about the way the circulation works is like a pizza delivery person in a big city. On the really big roads (vessels) there are walls and you can’t walk up to the door of the house and pass someone the pizza.

But once you get down to the little suburban streets (capillaries), the design of the streets means you can stop, get off your scooter and walk up to the door to deliver the pizza (nutrients).

We often think of the brain as a spongy mass without much blood in it. In reality, the average brain has about 600 kilometres of blood vessels.

The difference between the capillaries in most of the brain and those elsewhere is that these capillaries are made of specialised cells that are very tightly joined together and limit the free exchange of anything dissolved in your blood. These are sometimes called continuous capillaries.

This is the blood brain barrier. It’s not so much a bag around your brain stopping things from getting in and out but more like walls on all the streets, even the very small ones.

The only way pizza can get in is through special slots and these are just the right shape for the pizza box.

The blood brain barrier is set up so there are specialised transporters (like pizza box slots) for all the required nutrients. So mostly, the only things that can get in are things that there are transporters for or things that look very similar (on a molecular scale).

The analogy does fall down a little bit because the pizza box slot applies to nutrients that dissolve in water. Things that are highly soluble in fat can often bypass the slots in the wall.

Why do we have a blood-brain barrier?

The blood brain barrier is thought to exist for a few reasons.

First, it protects the brain from toxins you might eat (think chemicals that plants make) and viruses that often can infect the rest of your body but usually don’t make it to your brain.

It also provides protection by tightly regulating the movement of nutrients and waste in and out, providing a more stable environment than in the rest of the body.

Lastly, it serves to regulate passage of immune cells, preventing unnecessary inflammation which could damage cells in the brain.

What it means for medicines

One consequence of this tight regulation across the blood brain barrier is that if you want a medicine that gets to the brain, you need to consider how it will get in.

There are a few approaches. Highly fat-soluble molecules can often pass into the brain, so you might design your drug so it is a bit greasy.

Another option is to link your medicine to another molecule that is normally taken up into the brain so it can hitch a ride, or a “pro-drug”, which looks like a molecule that is normally transported.

Using it to our advantage

You can also take advantage of the blood brain barrier.

Opioids used for pain relief often cause constipation. They do this because their target (opioid receptors) are also present in the nervous system of the intestines, where they act to slow movement of the intestinal contents.

Imodium (Loperamide), which is used to treat diarrhoea, is actually an opioid, but it has been specifically designed so it can’t cross the blood brain barrier.

This design means it can act on opioid receptors in the gastrointestinal tract, slowing down the movement of contents, but does not act on brain opioid receptors.

In contrast to Imodium, Ozempic and Victoza (originally designed for type 2 diabetes, but now popular for weight-loss) both have a long fat attached, to improve the length of time they stay in the body.

A consequence of having this long fat attached is that they can cross the blood-brain barrier, where they act to suppress appetite. This is part of the reason they are so effective as weight-loss drugs.

So while the blood brain barrier is important for protecting the brain it presents both a challenge and an opportunity for development of new medicines.

Sebastian Furness, ARC Future Fellow, School of Biomedical Sciences, The University of Queensland

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