A good night’s sleep might have less to do with hours on the clock than people think.

A new study from researchers at the IMT School for Advanced Studies Lucca suggests that dreams, especially vivid and immersive ones, can make sleep feel deeper and more restorative, rather than disrupting it. The study was published in PLOS Biology.

For decades, deep sleep has been seen as a state in which the brain is largely “switched off,” marked by slow brain waves, minimal activity and little awareness. Under that view, deeper sleep meant less brain activity.

Dreaming, by comparison, has usually been tied to Rapid Eye Movement, or REM, sleep and treated as a sign of partial “awakenings” in the brain.

The researchers said that creates a paradox. REM sleep involves intense dreaming and brain activity that resembles wakefulness, yet people often still report that this stage feels like deep sleep.

To examine that contradiction, researchers analysed 196 overnight recordings from 44 healthy adults. Participants slept in a laboratory while researchers monitored their brain activity using high-density electroencephalography, or EEG.

The data came from a broader project funded by a European Research Council Starting Grant that examined how different types of sensory stimulation influence the experience of sleep.

Across four nights, participants were awakened more than 1,000 times and asked to describe what they had been experiencing just before waking. They also rated how deeply they felt they had been sleeping and how sleepy they were.

The results showed that people reported the deepest sleep in two situations: when they had no conscious experience, and after vivid, immersive dreams.

By comparison, shallow sleep was linked to minimal or fragmented experiences, such as a vague sense of presence without clear dream content.

“In other words, not all mental activity during sleep feels the same: the quality of the experience, especially how immersive it is, appears to be crucial,” Giulio Bernardi, professor in neuroscience at the IMT School and senior author of the study, said.

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

The researchers also found another pattern over the course of the night. Even as physiological signs of sleep pressure gradually decreased, participants said their sleep felt deeper as time went on.

That perceived deepening closely tracked an increase in how immersive their dreams became.

The findings suggest that dream experiences may help preserve the feeling of deep sleep even as the body’s biological need for sleep declines. The study also points to the idea that immersive dreams may help maintain a sense of separation from the external environment, a feature of restorative sleep, even while parts of the brain remain active.

Bernardi said the findings could open a new way of thinking about sleep health and mental well-being.

“Understanding how dreams contribute to the feeling of deep sleep opens new perspectives on sleep health and mental well-being,” he 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. Rather than being merely a by-product of sleep, immersive dreams may help buffer fluctuations in brain activity and sustain the subjective experience of being deeply asleep.”

The researchers said the idea echoes a long-standing hypothesis in sleep research, and in classical psychoanalysis, that dreams may act as “guardians of sleep.”

The study was part of a broader collaboration between the IMT School, Scuola Superiore Sant’Anna in Pisa, and Fondazione Gabriele Monasterio, where a new sleep laboratory has been established to combine neuroscientific and medical expertise.

According to the researchers, the facility supports a multidisciplinary approach to studying sleep and the sleep-wake cycle, with the aim of better understanding how brain activity interacts with bodily processes.

They said the findings are an early step in that work and a foundation for future research into how brain-body dynamics shape sleep in healthy people and in people with sleep disorders.