Yo Ho Grench,
Sleep- and waking- are controlled by a few areas of the brain and has influence from the endocrine system. However, despite medical miracles, sleep is still a bit of a mystery to good old science. The two main brain parts thought to be responsible for being awake (and ultimately, getting to sleep) are the hypothalamus and brainstem (the corpus collosum)- in the endocrine system, your thyroid and sympathetic nervous system has an influence.
Yes, bi-polar can be connected to insomnia and unhealthy sleeping routines, but if you have no other characteristics of bi-polar, it's unlikely to have anything to do with it. It could simply be that you need to incorporate some relaxation techniques and proper 'wind-down' times.
Sleep can be influenced by a lot: lifestyle, diet & exercise. Also- look at how much electricity is in your home and what gadgets are left on standby at night time. I found this a massive influence on how I slept, as electrical items emit an electrical charge and while you don't consciously pay attention to them, the stray ions have a deep, humming down. While asleep, your brain can almost 'hear' them, which keeps its alert and doesn't allow it to completely fall in to a deep sleep. Consider the position of your bed and how much you like your bedroom- sounds silly, but if you don't like a room, you subconsciously avoid the activities that go on in that room.
Hope you get some sleep soon.
V