I need somewhere between 7-8 hours of sleep. I don't drink coffee and I exercise 3 times a week. I find sleep matters more in the long run. I can function on 6

I need somewhere between 7-8 hours of sleep. I don't drink coffee and I exercise 3 times a week. I find sleep matters more in the long run. I can function on 6 hours, but after a few months I'm burned out and I end up catching whatever cold/flu is going around.