At what age did your baby start sleeping longer periods at night?

Try making a very consistent routine before night sleep. Whatever you want to be a part of the routine is fine - bath, book, massage, song - along with changing diaper and feeding. Do everything the in the same order every night. When he wakes at night be extremely boring. No talking, no playing, no giggles. Just answer his basic needs. During the day when he wakes up make sure you are interactive, playful, and give him lots of attention. He will get a better sense that he is expected to have fun awake periods during the day, and not so much at night. You can let him cry a little bit - it is not abandoning him to leave him go for 5 or 10 minutes. Sometimes babies will wake and cry out, and in a few minutes settle down and go back to sleep. You can give him a little time to see if that is the case before you go to him. My favorite sleep book is Healthy Sleep Habits, Happy Child by Marc Weissbluth. He is a pediatrician and sleep researcher. Very helpful information. Good luck.