SLEEP SLEEP SLEEP Why do you elude me?

Now if any Mere knows the sleep deprivation that parenthood brings ...... BUT what happens when you have experienced uninterrupted and wonderful sleep for over a year only for it to be shattered.

I have two beautiful and delightful children, T who is 4 and E who is 19 months. I have had a good run with both of my children in terms of sleeping. T began sleeping through the night at around 9 weeks (without a push) and E at around 14 weeks .... (no kidding or bragging) I have had a good run ...... so now this brings me to my darling T who at 4 has suddenly decided that sleeping in his own bed is NOT HAPPENING, for the last month T has been coming into our room between midnight and 3am and setting up bed in our room on the very uncomfortable floor. I am torn between doing the right thing - taking him back to his own room and helping him to feel comfortable and SLEEP..... usually the latter seems to win lately, but the time has come to break this little habit he seems to have developed .... any ideas