toddler keeps waking up and sneaking into the lounge room?

Set your alarm and wake up before he does. Try getting up at 6am, if he is up at that time try 5:30am. If he is getting up earlier than you would like you can try putting him to sleep a 30 minutes later than usual. Changing a bedtime can sometimes help. Is it possible the sun is waking him up in the morning? You could try darkening his room so that he sleeps longer. A baby monitor might also help let you know when he wakes up. I had an Angelcare monitor that did a great job. It let me know when my kids left the bed. I used it for the longest time when I was getting my daughter's sleep schedule adjusted. The laser alarms are fairly inexpensive and will sound an annoying beeping noise if the laser line is broken. You could place it in the doorway to his room or the hall he goes down to get to the lounge room.

Put a gate up so he can't leave his room. Maybe invest in a better quality gate or teach him to not be so destructive if you're having trouble with gates. You could even put one above another so that he can't climb. Perhaps he needs to go to bed later so that he sleeps longer in the morning? Even just putting him to bed a half hour later could make a big difference. Does he have a lot of windows in his room? Try dark blinds or shades...a bright room makes it harder to stay asleep. The sun could be waking him (we had this problem with our daughter and once we put up darker shades she's been sleeping great ever since).

Maybe you could set your alarm for 5 or 6 one day, get up then spy on him to see what happens. Getting caught once is all it should take to deter him from doing it again.

What is wrong with him waking up, going into the next room and playing inside his own house?

Set your alarm for 6:00 and get up.

If none of the doors in your house have locks, install some.

Baby cam or closing the door to the lounge room.

My third child when 2 would also leave his room, not to play seemed like he was sleep walking. I found him in the basement after frantically looking for 20 min. He had left his room before but, I had always caught him. I ended up getting a door knob cover, he should be too weak to squeeze it to open the door but, you won't be.

Looks like http://www.amazon.com/Mommys-Helper-Door-Safety-Co...

Shut the door the room you don't want him in and lock it.

My 3 yr old started getting up and going into the living room at about 2.5. We installed locks up high on all the doors just IN CASE she would try to open it. Otherwise just try to listen and get your kiddo to wake you up first.

EDIT I really don't think you need to cage him in his room - my girls were potty trained by that age and going to the bathroom unassissted at night so that would never work. As long as he isn't up getting into mischief and playing nice I think he is fine.

-Get a gate for his room so he can't get out.

- Buy a baby monitor so you can hear him get up.