Dd 4 and lying awake

[mummynumnum]

Dd has been really goo sleeper since about 1yr of age. Went to bed at 7pm and slept till
6am. She still goes to bed for 7 but in recent weeks has started a couple of times a week just lying awake in bed for hours. Is not causing bother and stays in bed, bar going to the toilet, but the prob is she still wakes at 6 and is v tired and grumpy and poorly behaved when she does this. She is 4. Any tips on this and how to deal with it?

Happened again last night and woke up again at 6am, dog tired.

Could it be the heat ? My DD1 (6) has really been struggling to get to sleep at night - not traumatically but just lying awake. Likewise, is waking even earlier than normal because of the light.

So no tip, but only hope that it will pass when the weather does rather than be a phase for the next 6mths !