It started for DS at 8 months (typical: late developer in virtually everything but sleep problems...) and at 10 months we're still going strong. Two hour jaunts about the cot at 2am are a very regular thing. If your LO also took to practising his/her stuff in the wee small hours and couldn't 'unwire', how long did the phase last, and did it stop spontaneously? All contributions gratefully received!