A new study from Italian researchers suggests vivid, immersive dreams can make sleep feel deeper and more restorative, even when the brain is more active. The findings could help explain why some people feel they sleep poorly despite normal lab results.
Many people judge a good night’s rest less by the clock and more by how deeply they feel they slept. New research suggests that vivid, immersive dreams may play a surprising role in that feeling of deep, restorative sleep — even when the brain is actually more active.
In a study published in PLOS Biology, researchers at the IMT School for Advanced Studies Lucca in Italy report that certain kinds of dreams can make sleep feel deeper, rather than lighter, challenging long-held assumptions about what deep sleep looks like in the brain.
For decades, scientists thought of deep sleep as a kind of brain shutdown: slow, synchronized brain waves, little activity and no awareness. In that traditional view, the deeper the sleep, the more the brain is “switched off.” Dreaming, by contrast, has been tied mainly to rapid eye movement (REM) sleep, a stage with wake-like brain activity that was often seen as a partial awakening.
Yet many people experience REM sleep as a time of heavy, uninterrupted slumber. The new study set out to probe that paradox: How can sleep feel deepest when the brain appears most awake?
To find out, the research team analyzed 196 overnight sleep recordings from 44 healthy adults who spent multiple nights in a sleep laboratory. While they slept, the participants’ brain activity was monitored using high-density electroencephalography, or EEG, which measures electrical signals across the scalp.
The data came from a larger European Research Council–funded project on how sensory stimulation affects the experience of sleep. Across four lab nights per person, the scientists collected more than 1,000 carefully timed awakenings from non-REM sleep, a stage that can include anything from dreamless oblivion to rich, story-like dreams.
Each time participants were awakened, they were asked what, if anything, had been going through their minds just before they woke up. They also rated how deep their sleep had felt and how sleepy they felt upon awakening.
This approach allowed the team to link three things on a moment-by-moment basis: objective brain activity, the presence and quality of dreams, and the sleeper’s own sense of how deep their sleep had been.
The pattern that emerged was striking. Participants reported the deepest sleep not only after stretches with no conscious experience, but also after vivid, immersive dreams that felt rich and absorbing. In contrast, shallow-feeling sleep was most often linked to minimal or fragmentary mental activity — for example, a vague sense that something or someone was present, without clear images or a storyline.
“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” senior author Giulio Bernardi, a professor in neuroscience at the IMT School, said in a news release. “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 noticed a second, counterintuitive trend. Over the course of a normal night, the body’s biological drive for sleep — sometimes called sleep pressure — gradually declines as the need for rest is satisfied. Physiological markers of that pressure, measured in the EEG signals, steadily decreased as expected.
But the volunteers’ reports went in the opposite direction. As the night wore on, they tended to say their sleep felt deeper, not lighter. That subjective deepening closely tracked an increase in the immersiveness of their dreams.
The findings suggest that immersive dreams may help maintain a sense of disconnection from the outside world, a hallmark of restorative sleep, even as parts of the brain become more active and the raw need for sleep fades. In that sense, dreams could be helping to stabilize the experience of sleep from the inside.
Bernardi sees broad implications for how clinicians and researchers think about sleep quality.
“Understanding how dreams contribute to the feeling of deep sleep opens new perspectives on sleep health and mental well-being,” Bernardi added. “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.”
That idea echoes a long-standing notion in sleep science and even classical psychoanalysis that dreams can act as “guardians of sleep.” Rather than interrupting rest, they may protect it, shielding sleepers from noises, bodily sensations or internal brain shifts that might otherwise wake them up or make their sleep feel lighter.
The study was carried out within a broader collaboration among the IMT School, Scuola Superiore Sant’Anna in Pisa and Fondazione Gabriele Monasterio, which have established a new sleep laboratory to unite neuroscience and medical expertise. The facility allows researchers to track both brain activity and bodily physiology, offering a more complete picture of the sleep–wake cycle.
While the current work focused on healthy adults and non-REM sleep, the team sees it as a first step. Future studies could explore how dream immersiveness and brain–body dynamics interact in people with insomnia, depression, sleep apnea or other conditions where sleep feels unrefreshing despite normal lab measures.
The research also raises practical questions that scientists are only beginning to explore: Could therapies that influence dreaming — through behavioral techniques, medications or sensory stimulation during sleep — one day help people feel more rested? And might tracking dream quality, not just sleep duration and stages, become part of routine sleep assessments?
For now, the findings offer a new way to think about what makes sleep feel satisfying. It may not just be how long you sleep or how still your brain appears on a monitor, but also how fully your mind is immersed in its own inner world during the night — and how well those dreams stand guard over your rest.