Far from disrupting rest, dreams might actually make sleep deeper and more restorative, according to a new study published in the journal PLOS Biology. The findings challenge the long-held belief that deep sleep requires a brain at rest.
Rethinking Sleep and Dreaming
Conventional wisdom has linked deep sleep to a quiet, slow-activity brain state, while associating dreams with REM sleep and partial awakenings. However, neuroscience researchers from Italy have found evidence that the most intense dreaming often occurs during the deepest sleep phases.
The Study: Measuring Dreams and Depth
To reach this conclusion, scientists analyzed 196 laboratory sleep nights from 44 healthy adults. Using high-density electroencephalography (EEG), they recorded brain activity. Participants were awakened during REM sleep—often called dreamless sleep—and asked about their mental activity and perceived sleep depth just before waking.
The results were surprising. About half of the participants who reported no dreams described light, superficial sleep and were in a state near consciousness. In contrast, those who reported vivid, immersive dreams also reported feeling deeply asleep and having had restorative rest.
How Dreams Alter Perception of Sleep
“This suggests that dreaming can alter how brain activity is interpreted by the sleeper: the more immersive the dream, the deeper the sleep appears,” said study lead author Giulio Bernardi, a neuroscience professor at the IMT School.
The research indicates dreams may help maintain sleep quality by promoting a sense of disconnection from the external world, even while some brain regions are active.
Implications for Sleep Health and Insomnia
This discovery opens new perspectives for sleep health and mental well-being. If dreams help sustain the feeling of deep sleep, disruptions in dreaming could explain why some individuals feel they sleep poorly even when objective sleep metrics appear normal.
“Understanding how dreams contribute to the sensation of deep sleep opens new perspectives on sleep health and mental well-being,” Bernardi noted. The findings could have important implications for understanding and treating conditions like insomnia.
