Oct. 6, 2022 -- The comfort of feeling cozy and safe with the help of a weighted blanket may help promote sleep by inducing a release of melatonin, a hormone associated with sleep, a study of young, healthy participants suggests.
“We all know if we want to relax a bit or we need support from others, it’s really good if they give us a hug,” says Christian Benedict, PhD, associate professor of pharmacology at Uppsala University in Uppsala, Sweden.
“And I think this is somehow similar with a weighted blanket because the blanket activates our sensory system, and this system conveys information to the brain where it impacts certain structures that play a role in the regulation of melatonin,” he says.
“So the body feels ready -- now I’m protected so I can relax -- and that signals back to the brain that we are ready to initiate sleep, which is why it boosts the melatonin signal,” Benedict says.
The study was published online on Monday in the Journal of Sleep Research.
Melatonin Increases Higher With Heavier Blanket
The study involved 26 young men and women who don't have insomnia. Participants underwent two experimental sessions -- the first visit to the laboratory to serve as an “adaptation” night and the second for the experiment. The adaption night was to help participants adjust to the experimental setting, the authors say. Saliva was collected every 20 minutes between 10 and 11 p.m. while participants’ sleepiness was also assessed every 20 minutes using the Karolinska Sleepiness Scale both before the lights went off and between 7 and 8 a.m. the next morning.
Duration of sleep was also recorded using a special wearable device that measures many physiological indicators of sleep.
The researchers said they focused on "total sleep duration as an outcome" for this study, noting that increases in melatonin in the saliva samples they collected were greater between 10 and 11 p.m. when participants used the weighted blanket.
There was also an initial but short-lived increase in oxytocin levels when participants used the weighted blanket compared to the light blanket, but it was not statistically significant, the researchers said. (Oxytocin is the so-called “love” hormone that controls aspects of human behavior including childbirth and lactation.)
But differences in measures of sleepiness between the two blanket conditions were not different. There also weren't any significant differences in total sleep time when participants used the weighted blanket compared to the light blanket.
But as Benedict points out, people have a variable response to melatonin. For example, children with attention deficit hyperactivity disorder (ADHD) might have some benefit from it, as well as older people who no longer produce enough melatonin on their own.
Overall, most studies suggest that melatonin itself doesn’t promote sleep. Melatonin prepares the body and brain for the biological event of night, which includes sleep, but it works through a relatively powerful placebo effect: People believe melatonin will help them sleep and believing it makes it so, Benedict says.
And just because the body makes its own melatonin, it’s not necessary safe to use melatonin supplements, Benedict says. For example, if people are eating and have a lot of melatonin in their system, the melatonin tells the pancreas to stop making insulin in response to food as it normally would. As a result, they run the risk of having high blood sugar levels, which, over time, can be harmful. There is also a risk of children getting into their parent’s melatonin stores, and melatonin can prove extremely harmful to children.
Weighted blankets are widely available and are sold for therapeutic reasons. People should test the blankets before settling on one; if a blanket is too heavy, the effect may be suffocating instead of feeling cozy and safe.
Benedict also cautions that heavy blankets sold for therapeutic reasons are not cheap — in Scandinavia they cost up to $250 — so doctors might still want to recommend them for their patients with insomnia provided they can afford the blanket. Alternatively, people could consider buying more than one light blanket and pile the weight on as needed, he suggests.
“Our study is the first to suggest that weighted blankets may result in a greater release in melatonin [but] future studies should investigate whether the stimulatory effect on melatonin secretion remains when using a weighted blanket over more extended periods of time,” the study authors write.
It is not clear whether the increase in melatonin observed in the study is therapeutically useful, they said.