Washington - In the final weeks of pregnancy, when sleep and serenity are often so elusive, there are certain tried-and-true tips to help an expectant mother relax and rest: Do gentle yoga stretches. Tuck a body pillow between your knees. Sip a cup of warm camomile tea.
And maybe watch a YouTube video featuring a young woman speaking in a breathy whisper as she pretends to give you an ear massage.
"When I found those videos, oh, they were a godsend," says Melissa Shaw, 34, a retail manager from Oregon who gave birth to her daughter in November. "I was at that point in my pregnancy where I couldn't take anything to sleep and I was so physically uncomfortable. I was up all night, super jittery and agitated, and all of a sudden, finally, I'd found something that could soothe me to sleep and it wasn't medical and had no side effects."
Shaw was in her third trimester when a friend first pointed her to the videos on YouTube, and she learned the name for the physical reaction they induced: ASMR, or autonomous sensory meridian response, which is often described as a cascade of pleasant tingles that begins in the crown of the head and ripples throughout the body, instilling a sense of deep relaxation. (If you're someone who gets goose bumps when someone whispers into your ear or plays with your hair, that's ASMR.)
The niche phenomenon has increasingly crept into mainstream culture, most recently making its Super Bowl debut in a Michelob Ultra beer commercial starring actress Zoe Kravitz, who whispered into a microphone and tapped her nails against a beer bottle. On YouTube, a vast trove of tranquility-triggering videos posted by "ASMRtists" have amassed tens of millions of views.
But ASMR might have a particularly potent effect for pregnant women, as the hormone most closely linked to the phenomenon - oxytocin - is often elevated during pregnancy, and also plays a critical role during labor and breastfeeding.
A recent study showed that ASMR activates the same areas of the brain that have long been associated with bonding and soothing behaviors. That might explain why some soon-to-be moms are turning to ASMR, and why a small but growing number of ASMRtists are making videos - mimicking prenatal massage, or role-playing as doulas - that cater specifically to pregnant people.
"I have my favorite videos that I go to all the time, and there's just something so soothing and so soft about them," says Maria, YouTube's preeminent ASMRtist with more than 1.6 million subscribers to her "Gentle Whispering" channel.
Maria (who, like most ASMRtists, keeps her full name private to protect her security because her work sometimes attracts unwanted attention) is expecting her first child this month and says she was surprised to find that her sensitivity to ASMR has been notably heightened during her pregnancy.
"Hearing a motherly, soothing voice before I go to sleep has been very helpful," she says. "I watch the videos to distract myself from the worries about motherhood, and to help me fall asleep. I have so many pregnant ladies who write me messages saying that they're going through the same thing."
Such anecdotes come as no surprise to Craig Richard, a professor and researcher at the Shenandoah University School of Pharmacy in Winchester, Virginia, and the founder of the blog ASMR University. After years of gathering survey data about ASMR, Richard has his own ideas about why certain people, and pregnant people in particular, might be especially susceptible.
"Increasing levels of oxytocin happens naturally during pregnancy, and oxytocin is the brain chemical most associated with the triggers and stimuli of ASMR," he says. "When I'm asked why I think some people experience ASMR and some don't, my best guess is that I think the people who experience it are producing increased amounts of oxytocin."
Research on ASMR is still in its earliest stages, Richard says, but last year he co-wrote the first published fMRI study of the sensation, tracking the brain activity of 10 study participants at Dartmouth College by detecting changes in blood flow when they experienced ASMR.