Published on
25/03/2026 – 6:45 GMT+1

What makes a good night’s sleep – the hours you spend in bed, or what happens in your mind while you’re there? New findings suggest the answer may partly lie in your dreams.


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Carried out by researchers at the IMT School for Advanced Studies Lucca, and published in PLOS Biology, a new study hints that vivid dreams may actually make sleep feel deeper and more restorative, rather than disrupting it.

For decades, deep sleep was thought to mean a largely “switched off” brain, with slow waves and minimal activity. Dreaming, by contrast, has been linked to REM sleep, a stage where brain activity looks more like wakefulness. But the new data suggests that this belief may be too simple.

The deeper the dream, the deeper the sleep?

Researchers analysed 196 overnight recordings from 44 healthy adults, using high-density electroencephalography (EEG) to monitor brain activity during sleep.

Participants were repeatedly woken during non-REM sleep and asked to describe their mental experiences and rate how deeply they felt they had been sleeping.

Across more than 1,000 awakenings, the findings showed that people reported the deepest sleep not only when they had no conscious experience, but also after vivid, immersive dreams. By contrast, lighter, more fragmented thoughts were linked to a shallower sense of sleep.

“In other words, not all mental activity during sleep feels the same,” said Giulio Bernardi, senior author of the study. “The quality of the experience, especially how immersive it is, appears to be crucial.”

“This suggests that dreaming may reshape how brain activity is interpreted by the sleeper: the more immersive the dream, the deeper the sleep feels,” he added.

Why does this study matter?

The results of the study are significant as they may change the way scientists and sleep specialists think about sleep quality.

Up until this point, sleep has been mostly measured by use of objective markers such as brain waves, stage of sleep or total time spent sleeping – but this study reports on how the participants report their own sleep.

The researchers also found that as the night progressed, participants “paradoxically reported feeling that their sleep was becoming deeper”, even though biological markers suggested sleep pressure was decreasing.

This shift closely matched an increase in how immersive dreams became, pointing to a possible explanation: dreams may help maintain the feeling of deep sleep, even as the body becomes more rested.

“Understanding how dreams contribute to the feeling of deep sleep opens new perspectives on sleep health and mental well-being,” Bernardi said.

“If dreams help sustain the feeling of deep sleep, then alterations in dreaming could partly explain why some people feel they sleep poorly even when standard objective sleep indices appear normal.”

If dream quality influences perceived sleep depth, therapies could eventually focus not just on improving sleep duration or continuity, but also on the nature of dream experiences.