It's a tough one this. Tiredness is very hard to cope with. But their sleep patterns DO change, at 12 months you may find he can sleep through.
All babies move around a lot in their sleep, it's totally normal. Even at two years old I still find my daughter sleeping in all sorts of wierd positions ! I also find if she is tangled up in sheets and stuff it tends to wake her up, so she just sleeps in long pyjamas and I have the room around 24 degrees, no bedding.
It's also very common for babies to wake up lots of times during the night. Like adults they sleep in cycles, some deep sleep and some light sleep. Sounds like what is happening is your son is emerging from his sleep, waking up, and being unable to get himself back to sleep again.
What are your options ?
Do nothing and wait for him to grow out of it. He will, eventually.
Look at his sleep habits - how does he get to sleep in the first place ? Does he have a comfort object such as a blanket or pacifier or does he need to be rocked to sleep ? does he sleep with you or in his own room ? Basically you need him to be able to recreate the same conditions when he wakes up on his own - the more "self soothing" he can do, the better. Try encouraging him to fall asleep on his own when you put him down - you might need to stay nearby and stroke him or soothe him, but then gradually as the weeks go by you can move further away from his cot, but continue to talk to him, sing or whatever so he knows you are there. Eventually you shoukd find you can put him down and walk out of the room - he might play and fuss for a bit but will eventually fall asleep on his own. In my experience though 8 months is pretty young for this approach - at this age they still need a lot of cuddling and soothing to help them go to sleep.
Look at his room - is it too hot ? too cold ? does he have too many covers ? is it too noisy ? I found blackout curtains helped with the early morning waking (available from Spotlight)
Try one of the "sleep training" methods. The extreme is the "cry it out" method called Ferberising, where you put them down and leave them first for 5 mins, then 10, then 15 etc. Some people swear by it. Another version of this is to go in and see him when he wakes but just soothe him briefly then put him down again. Don't smile or make eye contact with him as this will tend to stimulate him. At first you might have to go in and out a few times but eventually he will learn you mean business and it's time for him to go back to sleep.
Finally you could consider sleeping with your son. Some families swear by this and believe that everyone gets a better night sleep as the baby wakes up next to his parents, not alone in a cot down the hall, and can snuggle himself back to sleep before you even notice.
One final tip - if your son has a pacifier he may be waking in the night because he can't find it and can't get back to sleep. I solved this problem by tying the dummy to a soft toy. It worked like a charm, BUT now my daughter is more addicted to it than ever ! May be better to get him used to another way of soothing himself to sleep.
I guess at the end of the day you have to experiment and find a solution that works for you. Every family I know has different ways of getting their babies to sleep and different ways of coping when they wake up, there is no "best way".