Looking back: what sleep does for body and brain
Over the past decades, several striking findings have highlighted why sleep is far more than nightly downtime – the many vital benefits of sleep for health have recently been summarised by Dresler’s group. A classic example comes from immunology: when people are kept awake after receiving a vaccination, they produce only half the number of antibodies compared with those who sleep normally. “A considerable part of the immune response is built during sleep,” Dresler explains.
Another important current line of research concerns Alzheimer’s disease. During wakefulness the brain accumulates potentially toxic metabolites such as amyloid-beta and tau. Amyloid-beta is a protein that can form sticky clumps, and tau is a protein that can tangle inside brain cells. Both can damage the brain if they build up too much. During deep sleep, the brain cleans itself using a system called the “glymphatic system.” Dresler’s team confirmed in humans what had long been suspected from animal research: periods of slow-wave sleep are followed by increases in amyloid-beta in the blood, evidence of this nocturnal clearance.
A third example comes from the body’s hormonal balance. In a remarkable study, a group of students tried a radically polyphasic sleep schedule: 20-minute naps every four hours, totalling just two hours of sleep per day. Most abandoned the experiment within days, but one participant persisted for five weeks. Although his sleep stages were surprisingly preserved, his growth hormone release collapsed by more than 95%. This hormone, essential for tissue repair and bone integrity, simply cannot be produced without sustained sleep.
And sleep function is not only about basic biology: also it’s cognitive aspects are clinically relevant. Nightmare disorder and PTSD, for instance, may benefit from lucid dreaming therapy – an approach already recognised by the American Academy of Sleep Medicine. Dresler’s group is testing methods how to induce this therapeutic but rare state of sleep, both in the sleep lab and at home using wearable EEG and REM-specific stimulation.
From noise to treatment
For almost a century, EEG has been the gold standard for studying sleep. Traditionally, researchers focused on its rhythmic, oscillatory patterns. But the group of Dresler also examines the “aperiodic” signal – the part that once looked like noise. Dresler’s team was among the first to apply this approach to sleep, showing that it reveals smoother more biologically realistic sleep cycles and even serves as a biomarker for conditions such as depression. These methods could help refine how sleep disorders are diagnosed, and treated.
Looking ahead: the age of wearables
If the past decade clarified what sleep does, the next may reveal how to monitor it at scale. Dresler expects wearable technology to transform the field. Until recently, sleep studies required overnight lab visits, complex equipment and extensive night shifts by trained technicians. Increasingly, high-quality wearable EEG allows thousands of nights to be recorded in participants own bedrooms.
With emerging devices, including in-ear EEG (big tech already holds relevant patents), Dresler believes millions of people could soon have access to regular sleep recordings. But he also warns of a downside: “orthosomnia”, the tendency to worry obsessively about one’s sleep scores. Technology must therefore be accompanied by clear guidance and realistic expectations.
Regular sleep timing is more important than perfect duration
Despite all technological advances, Dresler emphasises one simple insight: regular timing matters more than perfect duration. It is natural to wake up multiple times each night, and a sleeping 85–95% of the time you spent in bed is considered healthy. Sleeping “too perfectly” may actually signal sleep deprivation. In a world chasing optimisation, Dresler’s advice is refreshingly grounded: prioritise a stable sleep rhythm because your brain and body rely on it more than you might think.