THE WASHINGTON POST – The weighted blanket has risen in popularity in the past few years, with manufacturers and users touting its benefits, including helping with sleep and anxiety issues.
A recent study suggests a mechanism that could explain why weighted blankets seem to help some people sleep better.
The use of a weighted blanket may result in more melatonin – a sleep-promoting hormone produced by the brain – being released, the research reveals. Melatonin reduces alertness and makes sleep more inviting.
During the day, light that enters the eyes sends a signal to the brain’s “master circadian clock” – a region of the brain called the suprachiasmatic nucleus – which then blocks melatonin production by the pineal gland, a pea-size organ in the brain.
After the sun goes down, the suprachiasmatic nucleus releases its hold on the pineal gland, allowing melatonin to set the stage for the body to sleep. Core body temperature drops, and drowsiness ensues.
“I met many paediatric doctors and occupational therapists who told me about the magic effects of the weighted blanket, but we don’t know if it acts as a placebo or what,” said study author Christian Benedict, associate professor of pharmacology at Uppsala University in Sweden.
“This was one of the reasons I decided to do this study.”
In the study, 26 young men and women with no sleep problems or other medical conditions were asked to sleep in the laboratory with a weighted blanket one night and a light blanket another night.
None of the participants had a history of using weighted blankets. The weighted and light blankets corresponded to, respectively, 12.2 per cent and 2.4 per cent of each person’s body weight.
The researchers took saliva samples every 20 minutes between 10pm and 11pm to measure changes in hormone levels.
On average, the rise in melatonin was 32 per cent greater on the night the participants slept with a weighted blanket.
“Body sensations, including gentle pressure on the skin, can activate brain regions that can influence the release of melatonin,” Benedict said. “We believe that a similar mechanism accounts for the observed rise in melatonin when using a weighted blanket.”
Weighted blankets have weights such as metal chains or glass beads sewn into them, along with traditional stuffing, to apply even, deep pressure to the body.
Occupational therapists in the 1990s discovered that weighted vests and blankets had a calming effect on children and adolescents with developmental and sensory disorders. They later were used in adult mental health settings as a humane alternative to restraint and seclusion, which are known to cause physical and psychological harm to patients.
The concept of deep pressure stimulation goes back even further, explored most notably in the 1980s by American scientist Temple Grandin, who has autism and designed a Hug Machine as a way to relieve her anxiety.
It worked by gently squeezing her with padded boards. Other examples include swaddles for babies and anxiety vests for dogs, both used in a way similar to hugs to induce calm.
Applying a gentle pressure across large swaths of the body activates the autonomic nervous system, which regulates heart rate, digestion, breathing rate and other functions.
Specifically, deep pressure stimulation is associated with reduced sympathetic arousal, or fight-or-flight response, and increased parasympathetic arousal, or rest-and-digest response.
Research has suggested that deep pressure stimulation from weighted blankets, in particular, may improve sleep.
In 2020, neuroscientist at Linköping University in Sweden Håkan Olausson, and his colleagues performed a randomised controlled trial of 120 patients with psychiatric disorders, giving them a weighted blanket every night for two weeks.
The patients reported less severe insomnia, reduced daytime fatigue and better sleep maintenance throughout the night when sleeping with a weighted blanket vs a light blanket.
A 2015 study tested weighted blankets on 33 people with chronic insomnia, reporting that they slept longer, found it easier to settle down, and felt more refreshed in the morning.
And a study on two children with autism spectrum disorders demonstrated improved quality of sleep with weighted blankets.
“Weighted blanket use has increased dramatically in the last few years, but most studies have limited sample sizes,” said occupational therapist and co-author of The Weighted Blanket Guide Cara Koscinski.
“We cannot jump to big conclusions,” about the latest study, she said, but the observed melatonin increase “provides another piece of the puzzle”.
“This is a very interesting study, but it would be nice to see it replicated in a second cohort because it is not an obvious thing that melatonin should increase with a weighted blanket,” Olausson said.
Benedict supported the need for larger trials, including, he said, “an investigation of whether the observed effects of a weighted blanket on melatonin are sustained over longer periods.”
While the study observed an increase in melatonin, it observed no difference in participants’ sleep duration or feeling of sleepiness with use of a weighted blanket.
The researchers also measured oxytocin, a hormone released in response to physical touch that is known to induce feelings of well-being and calm, but saw no increase for the weighted blanket condition.
Users, like Aimee Walker Baker, say weighted blankets have helped with their health issues.
“I feel like I’m in a cocoon of safety,” said Baker, 50, of Bay Minette, Alabama, who sleeps with a weighted blanket every night. A car accident in 2016 left her with severe injuries, along with nightmares as a result of post-traumatic stress disorder.
“It took a couple nights to get used to (the weight), but once I did, I actually slept. Like, for the first time in over a year! It felt like a victory,” she said. DeAndra Chapman, 38, of Stockton, Alabama, received a weighted blanket as a gift from her husband to relieve her anxiety and restlessness during the night.
“The weighted blanket helps me to sleep because it’s like a constant embrace, “ she said. “I use my blanket whenever I sleep, including naps. It even goes on vacations with me.”
Keri Leach, 55, of Westerville, Ohio, uses her weighted blanket for insomnia.
“My issue has been waking in the night and not being able to fall back to sleep, and it’s helped,” she said. “It’s harder to use in the summer because it can get really hot.”
Along with people with sleep disorders, Koscinski says, those with autism, anxiety, arthritis, chronic pain and attention deficit-hyperactivity disorder also use weighted blankets.
She adds that they may work very well for some people and not at all for others.
A general rule is to choose a blanket that weighs less than 10 per cent of your body weight, and they should never be used on individuals who cannot remove the blanket on their own, such as infants, Koscinski said.