The mind is alert to relaxing words spoken by others when you're asleep, so much so that your heart beat slows down, new research shows.

Hearing words like "relax" and "easy" spoken while asleep appeared to help put study participants into a deeper sleep and slowed their heartbeat, while words deemed not to be relaxing did not, scientists report.

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The findings suggest that "the brain and the body are connected even when we cannot fully communicate, including sleep," said Athena Demertzi, of the GIGA Cyclotron Research Center at the University of Liège in Belgium.

The study involved use of an electroencephalogram (EEG) to monitor heart activity in sleeping people. The time elapsed between heart beats lengthened when people heard the relaxing words spoken, even though they were not awake, the study found.

"Both brain and body information need then to be taken into account for a full understanding of how we think and react to our environment" while asleep, Demertzi said in a university news release.

The findings echo those of a 2021 study, which also found that "relaxing words increased deep sleep duration and sleep quality, showing that we can positively influence sleep using meaningful words," according to the news release. That study was led by Jonas Beck, of the University of Fribourg in Switzerland.

The study was published recently in the Journal of Sleep Research.