I also have this problem, it is because our health too weak, if use another view to explain is becasue our blood circulation is not good enough.
- weak socks to sleep.
- the root of the problem is to keep up our body stronger, but I find very difficult to do, even I am not a "selection food taker" i.e. it eat most of the food, not the one this not eat and that not eat.
- try to do some physcial exercise.