What you're describing is not insomnia, it sounds much more like a circadian rhythm disorder. I'm not just being pedantic, it's important to understand the differences between the two because the treatments can be significantly different. For instance, it's generally not wise with circadian disorders to medicate to sleep, the sleep you get won't be restful because your body is pretty much convinced that 1AM is a good time to be wide awake.
A small dose of melatonin taken at the right time of day (some experimentation is necessary, it could be as early as first thing in the morning) helps some people get their natural melatonin production on the right track. Bright sunlight first thing in the morning can also be effective. Of course, for many there is no effective treatment and you just have to learn how to deal with it best you can.