I did better with taking co-q-10 in the morning. For a long time, I couldn't tolerate melatonin. I would feel like I wasn't fully awake for up to three days after taking it. When my health improved enough that I could tolerate it, I still needed co-q-10 in the morning to feel fully awake.
Co-q-10 is the co-enzyme of melatonin and wakes your brain up in the morning. It is made in the body in a complex (17 step?) process. A bottleneck at any stage can leave you deficient, so many people are deficient. If you take co-q-10 in the morning, your body will produce a small melatonin spike about 12 or so hours later. If you take melatonin, it does not increase production of co-q-10. So taking co-q-10 can do a lot more in terms of healing both sides of waking/sleeping cycle of the brain chemistry. It is also gentler/subtler than melatonin.
Lots of people use melatonin to good effect, so I'm not trying to knock it. Just trying to expand on the topic of nutritional supplements and brain chemistry wrt the waking/sleeping cycle. Thanks for bringing this up. :-)