Weird things are happening to my dad after my brother died.

So My brother died after a long illness on 19 July this year. After that every night my dad wakes up around 2:30 am hurriedly and says that he felt like someone is pinching him or grabbing his leg or someone is telling him to wake up. Yesterday he woke up and he said someone asks him to wake up and that thing was scolding him. He is really scared to sleep now. My dad is a heart patient and already had two heart attacks. I am very skeptical when it comes to these things but also i am really worried.

What should we do? Please help