Is it okay when a dementia patient is sundowning and when he opens his eyes he eats if he is given food but sleeps after few minutes?

Sundowning doesn't mean a person is sleepy it means that the symptoms of Dementia seem more prevalent. Usually late afternoon evening. Some get agitated some get more confused.

We need more info. How is your patient during the day? Is this something new that he sleeps more often that he is less hungry? What other health problems does he have?