How Can Hallucination Be Treated?

My father had pneumonia and had to be put on a ventilator so to prevent him from gagging on the tubes they had to insert into his throat they sedated him heavily. Well after a few days he was able to have the ventilator removed. Now my father can not sleep every time he closes his eyes there are spiders, demons, worms and other such terrifying creepy crawlies. He’s scared and almost in tears. How long before these visions pass? I’m seriously worried. What can I do to help? Self hypnosis maybe? Anything at all?