E.K.
I agree with a lot of the moms that naptime is sadly drawing to an end. My daughter stopped napping when she was about 2 1/2, and she started sleeping WAY better at night! It could be growing pains, or wanting attention, or a lot of things. To this, I say, try a lot of different things. They make Calms Forte for kids - which is a homeopathic remedy that can help with restless sleep (if he's having trouble staying asleep). I make a night time tea for my daughter of Chamomile and Fennel, but you can buy pre-made children's night time teas as well. Another good thing is to wear them out as much as possible during the day so they're just too tired at night to protest too much. I start my daughter's bedtime routine a good 2 hours before it's actually time for bed. We take a bath (if she needs one), get in our pajamas, make tea and toast, & read books. When it's time for bed, she lays down her bed (which is in our room), I lay down on mine, and I don't answer her, other than saying, "go to sleep". I put her sippy cup of water next to her bed, so she drink some if she's thirsty.
I hope that the simple process of eliminating naps will be enough to help him sleep better. If not, there's vitamins and herbs and homeopathics. Good luck!