How can I sleep more deeply during a nap?

Hi. So I have been napping everyday in addition to some other practices (I teach English at a university in China, which gives me an obscene amount of free time).

I set an alarm to wake me in 1.5 hrs, but I often wake up with at least a half hour remainting. The dreams I can remember are usually short, fragmentary and fuzzy around the edges. Is it possible that these are nrem dreams? If so, how can I stay asleep through a full sleep cycle and get those fat, juicy dreams that naps should afford?

I know that I could drop a little melatonin 20 min before the nap, but this would not bode well for my precious and brittle circadian rhythm. Do you guys have any suggestions for keeping me under without making me groggy all day, etc.? I wear ear plugs and warm socks already.

Also, I notice that when I wake up from these dreams, my heart is usually beating harder and faster than I’d expect, even if the dream was not especially arousing. What’s up with that shizzle?

Thanks