Just one night of four hours of sleep can reduce natural killer (NK) cells —which fight cancer—by up to 70%.
Occurs more frequently in the second half of the night. This stage is essential for "emotional first aid," helping to process traumatic events and foster creative problem-solving by making novel neural connections. Critical Health Impacts of Sleep Deprivation Why We Sleep by Matthew Walkerrar
Chronic lack of sleep is a key risk factor for Alzheimer’s disease as it prevents the brain from clearing toxic amyloid proteins. Just one night of four hours of sleep