DS, who turned 9 months old one week ago, is suddenly waking every 40 mins in the early part of the night, then every two to one hours for the rest of the night and the wake ups are looong, twice this week I have had to sit with him for two hours waiting for him to go back to sleep (screams if I leave the room). He was previously waking just once at maybe 2an for a quick feed then straight back to sleep til morning. We went through a phase at 4months of him waking hourly which nearly destroyed me. Is this another regression? How long will it last? And how do I get through? Going back to work soon so need to sort it out!!