It's an interesting thought re the SAHM. I think that it depends on the individual. My son is a bad sleeper - always has been since he was born and we have tried everything. When he was 4 months old, I was ready to give him back as I was getting up all through the night and he would only sleep for 20 mins during the day - on the advice of a sleep school, we were letting him cry for hours at night (I wouldn't do it again - it didn't work and has created bad associations with sleep for him) and my life felt totally out of control. So I went back to work two days a week for a break! And it did me the world of good. However, the constant lack of sleep and stress of a fulltime job (DS is 2.5 now) does make me cranky at night especially when he won't go to sleep....so I think that it does mean that your tolerance may be slightly less - but on the other hand, I knew that I had a respite on the days that I went to work so I dealt better with him for the days that I was at home.