Draining battery after notification

[Felisung]

After I lock my tablet and walk away. I would get a notification after i get it, instead of going back to sleep or turning off (black screen) it stays on with the light etc. Because of this my battery will go from 100% to 15% in about 2 hours. Is there a way to change it so that after I get a notification it will go back to sleep after 5 seconds and such. It is really annoying because every time I get a like on Instagram or a Facebook message or even a game notification it will stay on.

Any kind of advise will be appreciated as I am new to this android world. Thanks