I want to start by saying I agree with Geetika K.'s description of the routine she started with her boys :)
Your son's sleeping behavior is very normal and common for a 5mo, especially for a boy. I don't know if anyone has ever told you, but the clinical definition of "sleeping through the night" for a baby under 12mo is 5-6 hours. And his naps are also normal for his age. I remember getting SO frustrated with my kids when they came into that phase! At least I felt a little more prepared for it the 2nd time around.
It's not usually recommended to do any kind of sleep training with a baby under 6mo, and I think that's even too young. Babies go through so many transitions and develop so rapidly that I know people who have done the expensive sleep training with their 5, 6, 7 month olds, only to have it all fall apart at the next stage of development. 6-12 months is a HUGE milestone period, with sitting up by himself, crawling, pulling to stand, cruising and walking, and most of these usually affect sleep in some way (even if it's small).
The better thing to do is to develop a routine with him and adjust your attitude towards his sleeping personality. I know it's hard right now with school and life in general, and I know it's easier said than done to subscribe to the whole "this too shall pass" and "he's only going to be this little..." but they really are true.
You could also try transitioning him into his own sleeping space and see how he does. We started with naps (actually at about his age; when they started rolling is when I got uncomfortable) to get them to used to sleeping in a different bed, their own space. When that went well, I started them in the crib for the first part of the night, then finally moved to putting them back in the crib after a night nursing (or 2 or 3).
There were 2 things that really helped me turn the corner:
- Changing my attitude towards night parenting (Dr. Sears has a wonderful section of this in one of his books)
- Elizabeth Pantley's No-Cry Sleep Solution (because there are so many great suggestions!!!).
Here are a couple of great articles to help with nighttime parenting:
- http://www.askdrsears.com/topics/sleep-problems/8-infant-...
- http://www.askdrsears.com/topics/sleep-problems/night-wea...
It does get better, and one day, you'll look back and wonder when things started to improve because it'll be gradual. But it may get worse before it gets better, and that's when the open mind is so important :)
Good luck with everything, and I hope you do well in school despite your sleep challenges!