2 boys, usually good sleepers, now waking up 1.5 hours earlier than usual. need advice

[notsoladyjess]

sorry, i know there have prob been loads of postings like this.
I have 2 boys, 2.9 and 1 yr old - both slpet through from 3-4 months and have slept til 7.30-8 most of the time. In the last 2 weeks they have been taking it in turn to wake at 6.10am. they then wake eachother up (in separate rooms but the sound travels). ds1 used to just chat to his toys for up to an hour but now he shrieks my name and demands i go in and get him.
I know 6am might not seem too early for some but it is not what i am used to!! has anyone got any tips? or please just tell me it is a phase and it will pass!! they both sleep in rooms with blackout blinds and curtains, ds1 has 1 hour sleep after lunch, ds2 has 2 hours sleep then, ds1 goes to bed at 7.30ish and ds2 at 7pm.
They have recently started at a new nursery and ds1 will not sleep there at all during the day - rather than making him sleep later it is making him wake earlier. i know they are a bit unsettled but they have never reacted like this to other changes before.
any ideas?