It is that time of year when sleep starts to be disrupted by the changing of seasons. Where you live, it might be getting warmer or cooler. Where I live, it is pretty warm in the evening when our kids go to bed, but by morning it is quite cool in their bedrooms, which can wake them up early.
If your child or children are waking early right now, consider that environmental factor. If that is a possibility, try to problem solve. If you have an older child, consider adding a blanket or switching a blanket for a heavier one. We did that with Brayden, but he still kicks the covers off in the night.
Another thing we have done is changed pajamas for the night. A few weeks ago, a t-shirt and shorts did the trick. We are having to move to warmer pajamas, and I have found Brayden is waking earlier than usual each day unless he is wearing a certain pair of pajamas. So experiment and find what is best for your child right now.
Another thing to do is to tweak the thermostat at night. I personally don't want the heat on in the night because it still gets warm enough in the day that we would then need the central air on. However, it is getting cold enough at night that we do need the air. If you have a programmable thermostat, you might need to change your settings. What worked in the winter might not work in the early fall.
Also, be aware that at this time of year it is a very dynamic process. What worked a week ago might not be enough now.
This can be a frustrating time of year, but keep in mind that it should be relatively short and you can get back to normal. Being aware of it is half the battle.