by Using a weighted blanket before bed can increase the body’s production of sleep-promoting hormones. melatoninsuggests a small study.
However, it’s unclear at this point why thick blankets can increase melatonin levels and whether this significantly improves people’s sleep quality, the study’s authors said in a report published Oct. Journal of Sleep Research (opens in new tab).
“This is a very interesting study, but it would be nice to see it replicated in a second cohort because it’s not clear that melatonin should increase with a weighted blanket.” Hakan Olausson (opens in new tab)a neuroscientist at Linköping University in Sweden, told the Washington Post (opens in new tab).
Melatonin helps the body go into sleep mode, where body temperature drops, metabolism slows, and levels of the stress hormone cortisol fall; melatonin also increases drowsiness in the hours before bed. Melatonin levels usually rise in the evening, peak at night, and decrease as morning approaches. BrainFacts.org (opens in new tab). This is because some of brain Synchronizes melatonin production, called the suprachiasmatic nucleus (SCN), with the time of day.
Related: Can you make up for lost sleep?
The SCN does this by monitoring light-related signals from the retina. The bright light asks the SCN to send electrical signals to other brain structures, which then transmit the message from the spinal cord to the organs. This chain message eventually reaches the pea-sized pineal gland and stops melatonin production. Conversely, dim light and darkness remove the brakes on the pineal gland and speed up the production of melatonin.
According to a 2005 review, in addition to light, environmental factors such as timing of meals, physical activity, and social interactions can also be affected when melatonin is produced. Journal of Biological Rhythms (opens in new tab).
That’s why scientists wondered if a different sensory cue — the pressure of a weighted blanket — could affect melatonin production.
To explore this question, 11 women and 15 men in their 20s were asked to sleep several nights in the lab – once under a light blanket and once under a weighted blanket to acclimatize. None of the study participants suffered from insomnia or had previously used weighted blankets.
During one session, each participant ate dinner, sat in bright light for two hours, and then sat in dim light until the lights went out at 11 PM. An hour before the lights went out, they were getting under either the light blanket or the weighted blanket. At that hour, the researchers took saliva samples every 20 minutes to monitor each subject’s melatonin levels. (Saliva melatonin concentrations usually about 30% (opens in new tab) of those found in a person’s bloodstream.)
While the study authors couldn’t show why, the study noted that when under a weighted blanket, participants’ melatonin levels increased an average of 32% more than under a light blanket. Moreover, using a blanket did not appear to affect participants’ sleep; both scenarios had the same degree of sleep before and after waking up, and their total sleep time was the same in both scenarios.
“Future studies should investigate whether the stimulating effect on melatonin secretion is observed on a nightly basis when using a weighted blanket frequently for weeks or months,” the study authors wrote. “Whether the observed increase in melatonin is therapeutically relevant for the previously described effects of the weighted blanket on insomnia and anxiety remains to be determined.”
Given that people’s circadian rhythms often deteriorate with age, it’s also unclear whether the observed melatonin increase would be seen in other groups, including older people, according to a 2019 review. International Journal of Environmental Studies and Public Health (opens in new tab).
