These are also the times that I suffer the most form anxious thoughts, and when I tend to over analyse events from throughout the day. I also have an annoying habit of waking up at exactly 4.15 AM if I am particularly anxious.
I've got several methods that I use to help lessen the thoughts. The first is by listening to the first bit of one of those self hypnotism mp3's. This is the bit that usually involves deep breathing techniques and muscle relaxation. These often put me to sleep.
If the thoughts are more persistent, I try to interrupt them by telling myself to stop (not usually out loud though ) and blink slightly longer than usual. This has to be repeated many times sometimes, but eventually seems to work quite quickly.
The other thing I do is listen to some quite loud but soothing music. I find it hard to concentrate on the negative brain chatter, and the music is relaxing, and again sometimes puts me to sleep.
The final method is to imagine a relaxing place such as a beach or forest. You have to imagine the temperature, the weather, your surroundings, sights and sounds etc... and try to imerse yourself in this imaginary world.