Ds did something like this but if I remember rightly, he was a bit older. I wouldn't have minded, but nothing I did made a jot of difference, so in the end I left him to get on with it, unless he got really upset. I think it became a habit tbh.
Could he be overtired. My youngest did that and I read up on it so much and most sleep espert put it down to being over tired and not being able to settle to sleep. Just a thought might be worth trying to put him to bed about 30mins earlier just to see for a few days
Are you cosleeping? My ds did this at nine months and so does dd (8 months) now and I've always presumed it's because we cosleep and they wake up when I'm not there. It only stopped with ds when dh started putting him to bed (19 months, I think). I find that sometimes dd sleeps through more if she is more tired (rather than less). Also, if I can resettle her fast the first time - before she is properly awake - she is less likely to wake again.
- Has his diet changed lately - could he be getting trapped wind? (On the rare occasions our DS wakes in the evening I think it is usually that).
- Is he cold as uberalice said?
- Is he getting enough sleep in the day? - if he is napping less well for some reason it may be making him tired and paradoxically more restless when he goes to bed. He hasn't started nursery recently or anything has he?
- Could something be waking him? - e.g. noisy heating pipes or something?
- Also apparently around the time of learning some new skills they can become restless sleepers for a while. Has he recently started crawling or cruising? If so it might be linked to that - it might even be giving him restless legs or something if he is doing "new" types of exercise. If so there's probably not much you can do except wait it out...