why cant my father sleep

i really need this to tell me why my dad cant sleep he wakes up in 2 a clock or 5 in the morning there are some months that he left his job he was a littel bite tens but not like this he's just like difrent person he whas to a psikolog and he gave him som pils named citalon alison anti depresion he had a problem he was always thinking of selfkilling or to do something bad that was part of him's thinking but he didn't take it so serios untill these days then he went to a psikolog as i mention erlyer i gues its a trauma when he was a solder he saw a killd person he keept it inside and as he's getting older he;s becoming whorser but he was never like this he acts weird i dont gett this is it from the pils or what you suggest me to do and sure i have to mention that he;s not working and a big deal to him is that he wont plase the family he's taking this to serosly may you teel me give me advice what to do what to say him to change the behavior he alweys listens to my advices pls heelp me .