What is Intrinsic photosensitive retinal ganglion cells (ipRGCs)?

There are special cells in your eyes called intrinsic photosensitive retinal ganglion cells, or ipRGCs for short, they help you know when it's time to sleep and wake up.

Think of ipRGCs like tiny sensors inside your eye that can feel light, even if you're not looking directly at it. They’re like the little helpers who tell your brain, "Hey, it’s getting dark, time to go to bed!" or "Look, it’s bright outside, time to wake up!"

These cells are especially good at sensing the kind of light that comes from the sun, like when you're playing outside on a sunny day. They send messages to your brain through your eyes, helping your body know when to be awake and when to rest.

IpRGCs work all day long, even if you’re not paying attention. They help set your body clock, so you feel sleepy at night and energetic in the morning, just like a little sun sensor inside your eye!