Simple off the shelf stuff like Zyrtec antihistamines work well, but if you want to get up at say 4am for a fish, take a half only, otherwise you won't wake up til 7am
I've been a shocking sleeper for years and tried a lot of prescriptions, but most of them are barbituate derivatives, so when you wake up you feel like herman munster for about an hour or 2, and thats bad for your job.
Also I have found that natural relaxants are OK, Zinc and magnesium supplements tend to relax muscles and assist with your natural immunity system. I have taken both for a few years now and have not suffered a bad flu.
Definitely exercise in the mornings works, it sets your system into a healthy rythym and by 10pm you are stuffed and happy to go to sleep.
I used to love night fishing at the pin too, but unfortunately the blokes I went with were big drinkers so inevitably you'd be half blotto by midnight and you'd pass out in the cabin