islamabad - Scientists have found that sleeping with the mouth open can be as damaging to teeth as sipping a fizzy drink before bed.

This is because breathing through the mouth dries it out - removing the protective effect of saliva, which has a natural ability to kill the bacteria in the mouth that produce acid. As acid levels rise through the night, tooth erosion and decay can begin. Sleeping with the mouth open can be as damaging to teeth as sipping a fizzy drink before bed, experts claim. The researchers believe the findings help to explain observations of dentists that people who sleep open-mouthed have higher rates of tooth decay.

Tooth decay in mouth sleepers is often worse at the back – this is because the back of the mouth tends to get drier than the front.

Patients with asthma and obstructive sleep apnoea are more likely to breathe through the mouth at night.   Under normal conditions, the pH level in the mouth – the measure of acidity or alkalinity – is a neutral level of 7.7.

But sleeping with the mouth open reduced this to a mildly acidic average a pH of 6.6, according to the study. In some people, acidity levels rose as high as 3.6.

This is high enough to erode tooth enamel and akin to having a glass of orange juice or can of fizzy drink before bed. If the mouth is open during sleep it dries out.  This triggers acid levels to rise, triggering tooth erosion

Men are most likely to be affected, as research has shown nearly a third breathe through their mouths while asleep, compared to just five per cent of women.

Joanne Choi, a sleep researcher at Otago University in New Zealand, and her colleagues created a device that can be clipped to the teeth at night.  This records acidity levels and transmits data to a computer.

She then asked 10 volunteers to sleep with nose clamps so they were forced to breathe through their mouths on one night.

On a second night, volunteers - who had an average age of 25 - slept normally without the clamp. Previous attempts to measure acidity have involved people waking up participants during sleep – which could disrupt the body’s rhythms and give unreliable results.

Ms Choi, a PhD student, said: ‘This study is the first to continuously monitor intra-oral pH changes in healthy individuals over several days.

‘Our findings support the idea that mouth-breathing may indeed be a causal factor for dental diseases such as enamel erosion and caries.’

Do more ‘selfies’ mean more relationship woes?

Posting too many “selfies” on social media might lead to serious problems with your romantic partner, according to a new study.

Researchers conducted an online survey of 420 users of the social media site Instagram. The users were aged 18 to 62. The investigators found that those who believed they were good-looking were more likely to post selfies, which are photographic self-portraits.

But the more selfies someone posted, the more likely the behaviour was tied to jealousy and arguments in their romantic relationship, along with emotional or physical infidelity, breakups and divorces, the findings showed.

“Although we cannot directly assume cause-and-effect due to the [study’s design], the results here show that body-image satisfaction can be detrimental to Instagram users’ romantic relationships, especially when users’ body-image satisfaction is promoted in the form of Instagram selfie posts,” study co-author Russell Clayton, an assistant professor at Florida State University in Tallahassee, said in a school news release.

According study author Jessica Ridgway, “the results from this study provide an avenue for future body-image research.” Ridgway is a visiting professor of retail merchandising and product development at Florida State.

“For instance,” she said in the news release, “future research could examine whether social media users post images of their actual selves or their virtual ideal selves, and whether such online behaviors are associated with similar negative outcomes found in our study.”