Park is a senior health correspondent at TIME. She covers the COVID-19 pandemic, new drug developments in cancer and Alzheimer’s disease, mental health, HIV, CRISPR, and advances in gene therapy, ...

Among an upended global health order, medical innovation pushes forward. Read how TIME chose the list of doctors, scientists and more. The past year has been a busy one for the global health sector.

The nervous system enables humans to react to their surroundings and to coordinate their behaviour. It comprises millions of neurones and uses electrical impulses to communicate very quickly.

Sleep happens in cycles that include three non-rapid eye movement (NREM) stages and one rapid eye movement (REM) stage, repeated 4 to 5 times nightly. Each cycle typically lasts 90 to 110 minutes. The ...