Sleep may play a key role in “clearing” the brain of toxins linked to the development of dementia. This conclusion was reached by an international team of researchers studying the so-called glymphatic system—a waste-removal mechanism in brain tissue that is thought to be most active during sleep, according to The Conversation.

Unlike the rest of the body, where the lymphatic system is responsible for removing metabolic waste, the brain has no classical lymphatic vessels. Only about ten years ago did scientists describe an alternative clearance pathway—the glymphatic system. It relies on the circulation of cerebrospinal fluid, which enters the brain’s intercellular space, “washes away” waste products, and removes them via venous structures.

Of particular interest to researchers is amyloid beta, a protein whose accumulation leads to the formation of plaques characteristic of Alzheimer’s disease. Animal experiments have shown that the removal of this protein from the brain increases during sleep. Human studies have also found that levels of amyloid beta in cerebrospinal fluid rise during wakefulness and decrease during sleep.

However, the picture remains complex. Recent experiments in mice have challenged the idea that the glymphatic system is active mainly at night, showing that it can also function intensively during the daytime. Scientists have not yet reached a consensus on the underlying mechanisms, especially as they apply to humans.

Nevertheless, evidence linking sleep to brain health continues to accumulate. In one experiment involving healthy adults, just one night of total sleep deprivation led to an increase in amyloid beta concentration in the hippocampus—a brain region critical for memory and one of the first to be affected in Alzheimer’s disease. This suggests that sleep is indeed related to the removal of toxins from the brain.

Special attention is being paid to chronic sleep disorders. For example, obstructive sleep apnea, in which breathing repeatedly stops during sleep, is accompanied by prolonged sleep deprivation and reduced blood oxygen levels. Both factors may contribute to the accumulation of toxic proteins in the brain. Sleep apnea has already been linked to an increased risk of dementia, and some studies show that treating the disorder improves the clearance of amyloid beta.

Insomnia—another common sleep disorder—is also associated with a higher risk of dementia, but there is still insufficient evidence on whether treating insomnia reduces the buildup of neurotoxins. Researchers emphasize that it is too early to claim that therapy for sleep disorders directly prevents dementia specifically through activation of the glymphatic system.

Overall, scientists agree that good-quality sleep is important for brain health and likely plays a role in its “cleaning” processes. However, it remains an open question whether improving sleep can be used in a targeted way to reduce the risk of neurodegenerative diseases. Research is ongoing, including studies of daily fluctuations of amyloid beta and tau protein levels in the blood of people with sleep apnea before and after treatment, as well as trials of insomnia medications that may potentially affect nighttime brain activity.

For now, specialists advise treating sleep as an important component of overall health and recommend seeking medical advice for sleep or memory problems without waiting for serious symptoms to appear.