Masaki & Amanda, OK, this may not come across as welcome advice to two doctors but when my youngest Jill was a baby, I had lots of insane moments. She didn't sleep well at all and between taking care of her and my 3 year old Gina, I was a walking zombi! The best purchase I ever made was to buy one of those wind-up swings. I would cushion her with pillows inside the sit-up swing since she was too young to sit by herself. I would put Jill in it and wind it up to the max (15 minutes). This would often do the trick putting her to sleep and giving me a chance to jump and out of the shower.
Sometimes I remember dozing off for 15 minutes while she would swing away. It would re-charge my batteries to make it through another day!
Not exactly medical advice...LOL.