October 6, 2022 – A study in young and healthy participants suggests that resting comfortably and safely with the help of a heavy blanket may help promote sleep by stimulating the secretion of the sleep-related hormone melatonin.
“We all know if we want to relax a bit or need support from others, it’s really good if they hug us,” says Kristian Benedict, PhD, assistant professor of pharmacology at Uppsala University in Uppsala, Sweden.
“And I think this is a bit like a heavy blanket because the blanket activates our sensory system, and that system relays information to the brain where it affects certain structures that play a role in regulating melatonin,” he says.
“So the body feels ready – now I’m protected so I can relax – and that signals to the brain that we’re ready to start sleeping, which is why it boosts the melatonin signal,” Benedict says.
The study was published online on Monday in Sleep Research Journal.
Melatonin increases higher with a heavier blanket
The study included 26 young men and women who did not suffer from insomnia. Participants underwent two experimental sessions – the first visit to the lab to serve as an ‘adaptation’ night and the second for the experiment. The authors say the adaptation night was to help the participants adjust to the experimental environment. Saliva was collected every 20 minutes between 10 and 11 pm while the participants’ drowsiness was also assessed every 20 minutes using the Karolinska Drowsiness Scale before turning off the lights and between 7 and 8 am the next morning.
Sleep duration was also recorded using a special wearable device that measures several 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 largest 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, the researchers said, but it was not statistically significant. (Oxytocin is the so-called “love” hormone that controls aspects of human behavior including childbirth and lactation.)
But the differences in measures of sleepiness between the two general conditions were not different. There were also no significant differences in total sleep time when participants used the weighted blanket compared to the light blanket.
But as Benedict points out, people have an altered response to melatonin. For example, children with attention deficit hyperactivity disorder (ADHD) may benefit from it, as well as older adults who no longer produce enough melatonin on their own.
In general, most studies indicate that melatonin itself does not promote sleep. Melatonin prepares the body and brain for the biological nighttime event, which includes sleep, but it works through a relatively strong placebo effect: People think melatonin will help them sleep and think it makes it so, says Benedict.
Just because the body makes its own melatonin, it’s not necessary to use melatonin supplements safely, says Benedict. For example, if people eat and have a lot of melatonin in their system, melatonin tells the pancreas to stop making insulin in response to food as it normally would. As a result, they are at risk of high blood sugar levels, which can be harmful over time. There is also a risk of children entering their parents’ melatonin stores, and melatonin can be severe harmful to children.
Weighted blankets are widely available and sold for therapeutic reasons. People should test blankets before settling on them; If the blanket is too heavy, the effect may be stifling rather than feeling comfortable and secure.
Benedict also warns that heavy blankets sold for medical reasons aren’t cheap — in Scandinavia they cost as much as $250 — so doctors may still want to recommend them to their insomnia patients provided they can afford the blanket. Instead, people can consider buying more than one light blanket and stacking the weight as needed, he suggests.
Our study is the first to suggest that heavy blankets may increase melatonin secretion [but] Future studies should investigate whether the stimulatory effect on melatonin secretion persists when a weighted blanket is used over long periods of time,” the study authors wrote.
It is not clear whether the increase in melatonin observed in the study is clinically beneficial, they said.