What is Suprachiasmatic nucleus (SCN)?

The suprachiasmatic nucleus (SCN) is like the brain’s built-in clock that helps you know when it's time to sleep and when it's time to wake up.

Imagine your brain has a little team of workers who are always watching the light outside. When it gets dark, they tell your body it's time to rest. When it gets bright again, they say, “Time to get up!” These workers live in a tiny area called the suprachiasmatic nucleus, or SCN for short.

Think of the SCN as a tiny light sensor inside your brain. It’s connected to your eyes, so when you see light, like sunlight in the morning, it sends a message to the SCN. The SCN then tells other parts of your body what time it is, helping you feel sleepy at night and awake during the day.

The SCN doesn’t just work with daylight, it keeps track of time even when there’s no light around. It’s like a clock that runs on its own, but it gets updated whenever you see light again, so your body knows when to adjust.