Dark Circles undery my eyes but i get plenty of sleep (6-7 hrs)?

So i've been getting these dark circles under my eyes for about 7 months now and i don't know what's causing them. Could overuse of screen-time(like iphone laptope) cause it because i got really addicted to this game on my phone? And also how would i get rid of the darkness under my eyes thanks you

How to add sound to a monitor?

How do I add sound to my monitor?
So I just plugged in my Xbox One into my Samsung computer monitor and it doesn't have an audio jack. I really want to hear the sound while playing games/watching netflix etc. And i have a headset with a 3.5mm audio jack (regular iphone jack size) and I don't know where to plug it in or how with what etc.