Many people don't sleep well, not necessarily because of insomnia, but because they do things before bed that keep their brains alert. Stress can cause cortisol levels in the body to rise, and high cortisol levels can suppress melatonin secretion, making it difficult for the body to enter sleep. The problem is, many people think that only work stress increases cortisol. In fact, browsing X, watching short videos, reading news, checking work messages, playing games, replying to emails, and even eating all send a signal to the brain: it's not time to rest yet, your body is lying down, but your brain is still working.