Screen fades in and out

[Android Question]

I have an HTC ONE + with AT&T for service. The phone is great so far but there is a problem that has come up recently. The screen lights up and dims about every 30 seconds. It has just started a few days ago and now my battery only lasts about 6-8 hours when it used to last 20-30 hours. I have downloaded an app killing app and norton free mobile anti-virus protection. I have manually killed apps and restarted the phone. I'm not sure what to do. Any suggestions?

 

[TheAtheistReverend]

If it were me, I would factory reset the device (be warned this erases all your data, back up your photos and such), and if it happens again I would contact HTC or AT&T to see about replacing it.