I believe the cause may be work-related and financial concerns.
When it first appeared, I put the sleep issues down to stress about these two things:
1) I was preparing a safety training presentation for executives and directors at one of our clients. 2) This required me to fly, in the past few years I have experienced anxiety during take off and landing. I'm fine once the plane is cruising as long as there's no turbulance. During this trip I wasn't anxious and I wonder if this is because my ADHD medication is working well. The training also went extremely well.
After the training and flight my sleep pattern was still bad. In fact, it got drastically worse. From falling asleep around 2am and getting 2 hour blocks, I was now falling asleep around 4am for less than 1 hour blocks.
The first night it appeared I had rejected a job offer earlier that day. I'm still confident I made the correct decision. While I can secure employment easily, I'm at a point in my career where I need to be discerning. Due to poor financial management when I was unmedicated, I don't have the savings I should to carry me for a month or so and this worries me.
That is a long answer, but hopefully enough detail. I have put a lot of thought and analysis in trying to find the cause myself in hopes of addressing whatever it is. As a contractor, I only get paid when I work and lack of sleep is prohibiting me from working full time. It's also leaving me physically incapable of teaching gym classes which loses me casual pay. This just adds to my financial concerns.