If one wakes up in the middle of the night to relieve oneself, what is the proper procedure regarding washing and the brachos of asher yatzar and hamapil?
The answer I was always told (need to look this up; I think it's Mishnah Brurah?) is:
A.) If you'd already fallen asleep, there's no problem of talking-after-HaMapil as you already slept some. B.) If it's just urination, no bracha is needed as it will be covered by the Asher Yatzar you say in the morning. Just go back to sleep. (Well, washing for hygiene purposes is always a good idea ...)
C.) If it's defecation, that requires its own asher yatzar, which in-turn requires washing "negel vasser" (right-left-right-left-right-left). So first do a hygienic washing with soap, (I believe it's preferable to then dry your hands), then do a ritual washing (no bracha), followed by asher yatzar.
UPDATE: From TorahMusings.com:
there are those who rule that one who goes to the bathroom several times during the night need not recite asher yatzar each time and need merely recite it once in the morning. (Rivevot Ephraim 6:123:2.)