How to naturally redden brown hair?

Ok well this is sort of like dying your hair but it's not exactly like it so maybe you will consider it. I use sun-in its this spray that you put in your WET HAIR and you either blow-dry your hair or sit out in the sun and wait for your hair to dry. After doing that a couple times your hair gets much lighter but its a gradual change so no one really notices unless you look back at the pictures before you used it. hope i helped! btw you can get the sun-in at any drugstore or department store (walgreens, cvs, walmart, target etc.)