I switched to training in the morning because I couldn't sleep at night after training in the afternoons. That was training without stimulants. I suspect it's not uncommon. I don't have a solid body of knowledge behind me, but I suspect it involves exciting the CNS too close to bed time.
Also, like others have said, if you're taking caffeine (or other stimulants) a few hours before your targeted bed time, that's likely a contributing factor to your restless nights. My approach is conservative, but I cut off all stimulants 10 hours before my targeted bed time.
I also have a circadian rhythm disorder, and have a routine for locking down entrainment to 24-hours. These tips could help practically anyone nail down a schedule in a few weeks:
Block out exposure to blue light at night (or a few hours before bed). If you're using a computer or smart phone, there are screen overlay applications that do this for you. Most popular would be f.lux. You can also wear blue blocking glasses. I wear a pair of BluBlockers, however, there are many options, including glasses that mostly just look like glasses.
Stimulate the natural release of melatonin by taking 0.5-to-1.0 mg of melatonin 3-to-5 hours before your targeted bed time. The timing and dose is dependent on the individual. The timing should be consistent (as in, skip the dose if you're 20 minutes late, and try again the next day). Large doses of melatonin apparently suppress melatonin release, and burn out receptors. At least so I've read.
Eat on a schedule. I suspect most people already do this (breakfast -> work -> lunch break -> work -> dinner). I've read that the important part is the timing of the first and last meals of the day, and everything in between isn't critical.
Cut out stimulants close to bed time. The rule of thumb I've seen is to stop caffeine consumption 8 hours before bed time. I'd treat that as a starting point and adjust from there. If you really want to test the caffeine hypothesis, go a week without any, see how things go, and then start adding it back in.
Switch your training to mornings (or whenever you wake up, in case any of you work late shifts).
You're free to try these out. I do all of them, but maybe just a couple together will do the trick for you. I really can't say, I'm not a expert. While nothing potentially dangerous is in this list, my advise should be viewed skeptically. Do your own research.