Why? Because taping your mouth shut forces you to breathe properly - through your nose.
People believe that by forcing themselves to breathe through the nose, they can avoid the negative effects associated with "mouth breathing". And some swear it's giving them the best sleep of their life.
But what good does slapping a piece of sticky tape on your mouth do? Do we need to be popping pills for a good night's sleep? And how soon before sleep should we be putting our phones away?
Sleep Well Clinic's Dr Alex Bartle, who specialises in sleep medicine, tells the Herald that there's no quick fix for a great night's sleep.
"You can't really control a lot of what happens at night, particularly during REM [rapid eye movement] sleep," he says.
"Taping would stop your jaw falling open and reduce snoring noise, but it's potentially dangerous if your nose is blocked," he notes.
"People are designed to breathe through their nose at night. Breathing through your nose reduces the volume or noise of snoring but it doesn't stop sleep apnoea."
He acknowledges that when it comes to sleep, breathing through your nose is always the best - but the best time to practice it is during the day.
"You will learn to breathe through your nose during the day - that starts in childhood," he says. "If you're a mouth breather as a child then you'll be a mouth breather as an adult."
But it's not just your breathing that affects your sleep. Preparing for a good night's sleep actually starts long before you close your eyes at night, he says.
No screen time
You should go to bed as relaxed as possible, says Bartle - and that means no screen time. Stop scrolling on TikTok, turn your notifications off and leave your phone in the lounge or kitchen rather than right next to your bed - then it won't be the first thing you reach for in the morning.
Room temperature
We've all been victim to sleepless nights in the relentless humidity this summer, so we already know that temperature affects our sleep.
Bartle says you should be sleeping in a "cool bedroom of around 16-18C" if possible for the best sleeping environment.
Limit fluids before bed
Eating and drinking too soon before bed can mean your digestion keeps you awake at night. Bartle advises not to drink too much before bed.
Exercise during the day
And it turns out that spending time outside during the day helps prepare your body for sleep later on.
"Go for a walk or a run outside during the morning, because that advances melatonin," he advises.
Your body will get used to associating daylight with being awake, and darkness with sleeping - that's why it's best to keep your bedroom dark and not to spend too much time there during daylight hours.
