My dad just got diagnosed with Alzheimer's and is now calling me every 15 minutes. I can't keep doing this. How can I get him to just check in with me every hour?

Just check your caller ID or leave it for voice mail. Then - without guilt - only answer a call or two a day as you can handle it, unless there is an emergency. You may want to read this:
https://www.agingcare.com/126209
Believe me, I know what you are going through.
Carol

My dad lives in my home-he call me every 15 minutes or less to come be with him-I am so tired because I work 12 hour days 5 days a week-then come home to this until bedtime and then he calls a few times during the night-after 2 or 3 times I usually can't get back to sleep. Any suggestion?