But orthodontists are concerned about the potential risks of these, which include damage to the roots of teeth, gum recession, loose teeth and teeth that need to be removed.

Customers are required to take teeth moulds themselves and work progressively through different sets of aligners sent to them in the mail, which move their teeth over time. A remote orthodontist oversees their progress through photos.

A lot of people underestimate how complicated changing teeth is because it ultimately affects your bite, which affects your jaw and your jaw joint and the muscles of your face.

A survey found 35 per cent of orthodontists who responded had treated a patient in the past 12 months following failed use of at home aligners.

2. The last thing I ate must have made me sick.

It is understandable to blame food poisoning on the last meal you ate, and this may be the case. But the food that caused your illness may have been eaten days before your symptoms appeared. Different bugs cause symptoms to start at different times after eating the contaminated food. You should consider all the foods eaten over the three days before symptoms first appeared.

3. Food that’s “off” will smell.

Most food-poisoning bacteria and their toxins don’t obligingly warn you of their presence with a particularly bad smell or taste. The “off” smell of putrefaction is usually due to relatively harmless bacteria, and food which seems normal in appearance, taste and smell can have enough harmful pathogens to make you ill. If in doubt, toss it out.

4. If you are vegan, you are unlikely to get food poisoning.

Even though meats, seafood, poultry, eggs and dairy are the leading causes of food poisoning, vegans are not off the hook.

Plants and plant-based foods can become contaminated as easily as any other food if they come into contact with bacteria found in soil, unclean surfaces or equipment, or food handlers who are sick or have dirty hands.

Contaminated bean sprouts, for instance, have been linked to outbreaks of E. coli infection. Raw rice can contain bacteria called Bacillus cereus that survives cooking. If rice is unrefrigerated for more than two hours after cooking, the bacteria can multiply and make you sick.

5. Refrigeration will kill off bacteria.

Refrigeration is important for slowing down the growth of bacteria, but it doesn’t kill it.

Cool hot food until it has stopped steaming before putting it in the fridge. Don’t leave food to go cold completely as slower cooling allows bacteria to grow. And make sure you eat or freeze leftovers within two to three days of cooking.

You are actually just switching your attention astonishingly quickly, over and over again. It is not only exhausting, but makes you even less efficient than if you did one thing at a time.

Dr Earl Miller is a neuroscientist and Professor of Neuroscience at MIT in the United States.

“People can’t multitask very well, and when people say they can, they’re deluding themselves,” says Dr Miller. “The brain is very good at deluding itself.”

Dr Miller says trying to multitask is an extra problem when you’re juggling similar tasks, for example talking on the phone while writing an email. He says it’s impossible to focus on both because they involve the same part of the brain, the part responsible for communication.

Multitasking makes you slower

Researchers have proven that trying to switch between too many things too often actually reduces your productivity.

The only time it is possible to multitask to any extent at all is when one of the tasks in habitual or automatic. Think: cleaning your teeth while mentally compiling your to-do list. But as soon as you need to focus on something new, such as discovering a sore tooth, your brain switches away from your to-do list.

Research Fellow at Deakin University’s School of Psychology, Dr Gillian Clark, says our brain doesn’t have capacity to allocate attention to everything all at once.

“This switching to and from is really inefficient,” Dr Clark says, “It means that we miss things, make mistakes and slow down on all the tasks we’re switching between. Multitasking generally lowers productivity.”

The University of Utah recently ran a comprehensive study to measure how well people think they can multitask, compared to how well they can actually do it. They concluded, “Perceptions of the ability to multitask were found to be badly inflated.”

What’s more, they said, “the persons who chronically try to multitask are not those who are the most capable of multitasking effectively.”

How to actually get more done

So if multitasking doesn’t help you get more done more quickly, then what does?

Doing one thing at a time, according to experts. It’s simple but powerful.

Here are some more tips on how to achieve that:

1. Create a block of time for each task

Most of us have to do multiple tasks within a day, so the trick is to create blocks of time for different tasks, where you can work undistracted by all the other tasks.

You could even set yourself appointments with each task – it seems to increase your commitment to getting it done.

2. Plan your day

Yes, unexpected things will come up, but planning allows you to allocate blocks of time for the tasks you know you have to do, while allowing some wriggle room.

3. When you’re at your desk, only work

If you know you like to procrastinate on news, websites or social media, then train yourself to do that away from your desk. Stand up and use your phone, if you must. That way, you create a habit where being at your desk means focused work.

The symptoms of depression can vary from person to person, and even in age and gender. Here are seven unusual symptoms to watch out for:

• Irritability

Dr Anne Fabiny, assistant professor of medicine at Harvard Medical School, says older men often show irritability or grumpiness as a symptom of depression. “So the stereotype of the grumpy old man could be a sign of a depressed old man.”

Women can also seem angry when they are actually depressed, and can lash out unexpectedly, or turn that anger on themselves in a deep self-hatred.

• Forced happiness

People with depression often try to overcompensate in social situations, putting on an extra happy face to cover up their sadness.

• Excessive alcohol and drug use

It is a tricky one to spot, but around a third of people with depression also have a substance abuse disorder – that is about double the rate of the general population. It can be an early sign of depression, as people try to cope with their feelings by drinking or using drugs.

• Loss of concentration

You find it hard to concentrate at work, which leads to stress and negative thoughts about yourself, which in turn feeds the depression. Difficulty concentrating, even difficulty following a conversation or a TV show that you used to love, can be a sign of depression.

• Physical pain

Some people notice the physical symptoms before they recognise the depression. Physical signs of depression can include:

- feeling tired all the time

- being sick and run down

- headaches and muscle pains

- churning gut

- significant weight loss or gain.

• Sleeping

If you are having new troubles sleeping, including falling asleep, and especially waking up before dawn, it could be a sign of depression. On the flipside, wanting to sleep all day is also one of the symptoms.

• Uncontrollable emotions

Feelings can burst out in unexpected ways with depression, with some people finding it hard to manage their emotions from one minute to the next. If you or someone you know is lurching from laughter to crying to anger to guilt in a short time, it may be a sign of depression.

Losing your temper much more quickly than usual is also a sign, as are seemingly over-the-top responses, such as crying over a tiny thing like spilling water or not being able to find a pen.

Even if you are unsure if your recent changes are signs of depression, it is worth looking into.

Top tips to make sure the sunscreen works

• Your skin should be clean and dry. If you have been swimming, or have sand on your skin from the beach, wash and dry yourself first.
• Thoroughly rub the sunscreen into your skin.
• Remember the tricky spots, especially the top of your ears, your scalp and the top of your forehead, where your hat often rubs against your skin.
• Wait 20 minutes before going into the sun to allow the sunscreen to bind properly to the skin.
• Cancer Council recommends reapplying 20-30 minutes AFTER you have been in the sun, a bit like a second coat of paint.
• Reapply at least every two hours and directly after swimming, sport, sweating or towel drying. Sunscreens labelled as water resistant are tested to be effective for up to 40 minutes of swimming, so it’s best to reapply these too.
• Check the use-by date on your bottle of sunscreen. If it is out of date, it will not be as effective.
• Make sure your sunscreen is stored below 30 degrees Celsius and out of direct sunlight. Keeping your sunscreen in your car glovebox in summer will reduce its effectiveness.

And of course, try to stay out of the sun altogether between 10am and 4pm in summer if you possibly can. In all seasons, check the UV levels in your area. A good weather app will often include the UV forecast.

Remember, sunscreen is your last line of defence. No sunscreen is 100% effective against the UV radiation that causes skin cancer.

It is not just Slip Slop Slap; it is Slip, Slop, Slap, Seek, Slide. Slip on a shirt, slop on sunscreen, slap on a hat, seek shade and slide on some sunglasses.