I take a nap in the afternoon once in a while, maybe like once in a month. My husband thinks I am lazy and puts me down for it. Does this really make me lazy because I know in other cultures it is important to take naps and I think it is just frowned upon in American society because it "ruins" productivity.
I do currently work two paid jobs and have an unpaid Internship (I put in about 50 hours a week for these jobs in total). I am also a currently a Graduate student in an accelerated all year program so I think I need the naps when I take them since the classes run at night for three hour intervals.

Your husband is a jerk.

I don't think anyone could possibly make a case to prove sleep is harmful.

The Mediterranean countries still have a siesta. Greece, Italy, Spain, and Monaco among others. Because they get some REM sleep midday, they have more energy later on, so they go out almost every night and have very active social lives. It blew me away seeing the streets busy after midnight on a Monday. Such is not the case for the hard working American.

Naps are good for you. That's why we make babies take them. ;)

Seriously though. When you take a nap it's because your body is telling you you need sleep. You have a lot on your plate. You're a busy lady. If you take a nap once in a while, that's a good thing, and your husband should realize that you need the rest because you work hard.

Continue to nap, and tell your husband that what he does with his time is his business, and that the things you do, that should be enough to show that you're not lazy at all, you're just tired.

Sleep well. :)