A doctor has urged people to replace their pillows at least every two years because bedding gets riddled with dust mites and bacteria that grows on yellow sweat spots.
Dr Karan Raj, from the UK, has taken to TikTok to share his expert knowledge to millions on the social media platform - and his revelations left many grossed out.
Alongside a video, which has since garnered 1.2 million views, he explains: 'You need to change your pillows at least every two years.'
'The average person sheds about 4kg of skin every year. Most of that ends up on your bed or pillow - a feast for microscopic dust mites.
He continues: 'A single dust mite has about 20 droppings each day, multiple that by the hundreds of mites living on your pillow.
Dr Karan Raj (pictured) has taken to TikTok to urge people to replace their pillows at least every two years because they get riddled in dust mites
The expert explained how the average person sheds about 4kg of skin every year - most of which ends up on your bed or pillow - a feast for microscopic dust mites (pictured)
He also went on to explain those nasty yellow marks and spots are actually a result of a build up of 'sweat and oil from your body' - the moisture of which can breed mould or bacteria (pictured, left and right)
'A build up of dust mite faeces can cause breathing and allergy-type symptoms.'
And when it comes to stripping the bed and pillow slips, many people are often greeted by unwanted nasty yellow marks and spots.
And while some have been left pondering what they could be, the doctor has the answer - adding that they are actually a result of a build up of 'sweat and oil from your body' - the moisture of which can breed mould or bacteria.
He goes on to say that you can test whether your pillow needs changing by folding it in half.
Dr Karan Raj (pictured) added that if you can fold your pillow in half and it doesn't spring back, then it needs changing
'If it doesn't spring back, it's dead,' he says. 'It's no longer keeping your neck and spine in alignment causing neck pain.'
'My pillow is older than me,' wrote one, while a second penned: 'I did not need to know this.'
A third added: 'I wish I didn't see this video,' while a fourth commented: 'Oh, I've had my pillow for about 11 years.'
Taking to Twitter, one person wrote: 'My pillow is older than me' (pictured)