这句话为什么要用过去完成时态

这句话为什么要用过去完成时态
He had had some recurring dreams.请问这句话为什么要用过去完成时?为什么不能说he had some recurring dreams.
我把前后文贴出来大家看.（第二段的第一句就是这句） 之前之后都是过去时,这句话为什么不一样?
It was not long,however,before he dragged himself out of his depression and back to work.In the hospital,he had seen a boy die of leukaemia in the bed opposite him,and it had not been a pretty sight.He realised that clearly there were people who were worse off than him.At least,his condition didn't make him feel ill.Whenever he felt like pitying himself,he remembered that boy.
He had had some recurring dreams.He dreamt that he was going to be put to death,which made him realise that there were a lot of worthwhile things he could do if he were to be set free.In another frequently occuring dream,he thought he could give up his life to save others:'After all,if I were going to die anyway,it might as well do some good.'
我知道这个deamed 是在 he dragged himself out of his depression and back to work.之前，但是为什么dremt 又用一般现在时呢？