Because of their capacity to distract, cellphones and sleep are not the best of bedfellows.
But besides keeping you awake, new research warns that bringing your smartphone to bed could literally shock you.
Shocked and burned
The report describes instances of people who were accidentally electrocuted and burned by phone charging cords.
"A charger relies on the contained transfer of a certain amount of electrical current," explained study author Dr Carissa Bunke, a paediatric resident physician with the University of Michigan C.S. Mott Children's Hospital in Ann Arbor.
But if that electrical transfer is not properly contained, unsuspecting phone users can end up shocked, burned and in some cases hospitalised, she said.
Bunke's team highlights a case in point: a 19-year-old woman who sought care at an ER when she experienced neck pain and burning after going to sleep.
While in bed the patient had inadvertently lay on top of a USB-charging cord meant for an Apple iPhone. The cord was an inexpensive off-brand type, which the patient had left plugged into an outlet, even though the "live" charging end was not actually plugged into her phone at the time.
The live end then came into contact with a long metal necklace the woman was wearing. That triggered a sudden burning sensation, along with "severe" pain around the patient's neck.
"In most cases," said Bunke, "a shock or a burn would only slightly damage the top layer of skin and could be addressed at home or at urgent care.
"In more serious instances, second-degree burns – those that penetrate to the second layer of skin – could cause serious externally visible injuries that require procedures such as skin grafts," she added.
In this instance, doctors found that the charger's electrical current had burned an almost perfect circle around the patient's neck.
"Because the burn is caused by electricity, the shock can be painful," said Bunke, who added that serious electrocution cases can even trigger irregular heartbeats, breathing difficulties or muscle damage.
"Treatment would depend on severity, but in most cases requires an initial visit with a physician, checks for internal and external injury or side effects, and follow up with a primary care provider or burn centre," she noted.
In this case, the patient was released the same day after being given morphine for her pain and antibiotics to prevent infection at the burn site.
But electrocution risk is not only a function of how or where phone cords are placed around the bed, said Bunke. The kind of charger used may also matter, she said, with cheaper knockoff cords potentially posing a greater risk than an original, branded plug.
Literally thrown out of bed
Why? "Evidence is mounting that generic chargers are not necessarily guaranteed to go through the same safety and quality checks as the branded versions," Bunke said.
Still, even brand-name cords can pose problems in certain situations, her team noted.
For example, Bunke and her colleagues also noted another cellphone electrocution case, in which a young man took his Apple iPhone equipment to bed.
In that instance, the plug was in fact an original Apple-brand cord. But he was electrocuted and literally thrown out of his bed, after a chain he was wearing came into contact with the cord.
Do cellphone chargers really use that much electricity?
Bunke and her team stressed that doesn't matter, pointing out that "even with a low-voltage device, if the current is high, then the electric shock can be severe".
Bunke's bottom line? "Do not sleep with your mobile device," she advised.
Don't take your cellphone to bed
"And avoid leaving the charger plugged in when it is not connected to a phone," Bunke added.
The findings were published recently in the Annals of Emergency Medicine.
Dr Leigh Vinocur, national spokesperson for the American College of Emergency Physicians, agreed with Bunke's advice.
"I'm guilty of this," Vinocur admitted. "I, too, have my iPhone plugged in next to my bed, because it's my alarm clock. I don't lay in bed with it. But certainly when I leave the house, I leave the cord plugged in. And truthfully, I've also bought cheap non-branded power cords on Amazon."
"So, this study opens my eyes," said Vinocur. "As a physician, a consumer, a mother, and as someone who has a pet in the house."
"And I would say that we all really have to pay more attention to this," she added, "which means looking for chargers that are certified, and making sure the power cords are not frayed. And not taking our phones into bed with us when we're asleep, and unplugging them when we leave the house."
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