@baj
Thank you for your comment, baj. It seems like you certainly have your challenges - and I'm so sorry that we both have these challenges to deal with. My husband can't cook anymore, occasionally helps me with my supervision. He too, has no short term memory. Turning off the tablet will most likely help with his sleep.
One thing that I do - I had read where dementia patients like music. I have a playlist of his favorite songs (4 hours worth) and we have a concert night during the week. He loves the music and sings along with the songs. I read that even if the dementia patient forgets who you are, they most likely will relate to music. Our concert night is very calming and relaxing for us both. Take care.