Lack of sleep not only makes you feel bad but also impairs the brain, potentially increasing the risk of Alzheimer’s and other neurological diseases. Researchers conducted a study with mice to understand how sleep deprivation harms the brain. They found that a protective protein, pleiotrophin (PTN), decreases with sleep deprivation, leading to neuronal death in the hippocampus, a region linked to learning and memory. This protein’s decline was linked to impaired maze navigation and object recognition in mice. PTN is also associated with Alzheimer’s and other neurodegenerative diseases in humans, suggesting it could be an indicator of cognitive impairment due to insomnia. This research reveals a new mechanism for how sleep protects brain function.