This is how often you should be replacing your toothbrush.

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Sheets. Pillows. Shower loofahs. Toothbrushes. Most of us use these items every single day without fail. But have you ever thought about how long you go without replacing or washing these things?

We have. And there’s an alarming amount of research out there that would suggest that, in the name of health, you should probably be replacing them a lot sooner than you are. Yes, the whole The Glow office are heading home to bin our shower loofah immediately.

Toothbrush

Dr Daniel Tong, a Dentist who practises in central Melbourne, recommends that you should change your toothbrush every three months. After three months of use, toothbrushes are less effective and don’t remove plaque from teeth as well. The bristles break down and loose their effectiveness in getting to all those tricky corners around your teeth. (Post continues after gallery).

According to research published in New York State Dental Journal, it is also important to change toothbrushes after you’ve have been sick or had the flu, as germs in your toothbrush can lead to further infection. An electric toothbrush like the Oral-B Triumph 5000 is a good way to ensure you’re brushing your teeth properly as it provides feedback after each use. Fancy!

Loofah

Because your loofah scrubs your dead skin cells away, they get caught in the fibres and bacteria has the potential to cultivate between showers. Delightful, isn't it? Each time you don’t dry your loofah (which is always if you're me) the bacteria grows.

Related: You've been washing your hair wrong all this time. Here's how to do it properly.

A study published in the Journal of Clinical Microbiology showed that loofahs can host and transmit pseudomonas aeruginosa, a bacterium that can cause disease in animals. (Post continues after gallery.)

Dr. Jessica Krant, M.D., board-certified New York City dermatologist, told the Huffington Post that if you've got an open sore or cut and are "too aggressive with the loofah," you could inadvertently be "forcing the particles into a wound." Ouch. As a general rule, if it smells or changes colour, bin it. But to get the most out of it, let it dry outside the shower after each use.

Sheets

There's a very good reason to clean your sheets more than once a month: Sheets are a breeding ground for dust mites because there are a lot of dead skin cells in them.

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We shed up to three kilograms of skin each year and, according to the Mayo Clinic, there can be anywhere from 100,000 to 2,000,000 dust mites living in your bed. So wash your sheets. Preferably every one to two weeks.

Pillow

Not replacing your pillow enough can make you sick. An allergy study in 2005 from the University of Manchester took samples from pillows with between one and a half and 20 years of regular use and found several thousand spores of fungus per gram of pillow. And, according to this research, pillows that are older than five years have twice as much mould in them when compared to pillows less than two years old. Breathing in bacteria from the mould can put your immune system under pressure. I don't know about you, but I can't even remember the last time I bought a new pillow. Hmm.

What is even more gross is that research shows after one year of use, 10 to 15 per cent of your pillow’s weight may be made up of dust-mite waste.

Dr Michael Breus, a Clinical Psychologist and Sleep Specialist, recommends that people replace their pillows every 18 months.

"But this can be longer for memory foam pillows. Regular poly fill or down fill pillows lose their structural integrity when your head is on them 365 days for 6-8 hours. Another way to tell if you have a dead pillow is to fold it in half. If is springs back it is still good." Dr Breus says.

Mattress

According to the National Sleep Foundation a good mattress will last you nine to 10 years.

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If your mattress shows signs of wear (tearing, ripping, sagging, damage), if you wake up with stiffness or soreness, or if you are tired after a full night of sleep, consider buying a new one.

Running shoes

Like everything, if you use it often it will wear out. With your runners, it depends on how far and often you run, and it's also dependant on factors like your body weight and foot type.

There are some telltale signs you need to replace your runners though, including if the outer sole has worn through into the white midsole, if the mid-sole is soft and collapses under pressure, if the heel becomes noticeably less supportive, if one of the shoes soles is asymmetrical when you wear them (compared to the other one) and if one or both of the runners won't stand up straight when you put them on a flat surface.

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If you feel aches and pains in your back, it is probably time to change your runners, shin splints and muscle problems can occur when your shoes are too worn out, and you can risk injury if you don't have supportive runners.