L.O.
We just had this same exact problem with my 6 year old daughter. She was calling me multiple times per night (she's not allowed in our bed, so that was not an option). In the beginning she made up excuses - I have to go to the bathroom, I don't feel good, I'm cold, etc., etc., etc.. After a few days of this, we had a heart-to-heart where I told her she has to tell me what is really bothering her because there is no way I can help her. If she says she's sick and she's not really, I can't help and the next time she really is sick, I'll think she's lying. She understood and confessed, "I'm scared." This didn't make sense to me, because she shares her room with her older sister - so she's not alone. She couldn't pinpoint what she was scared about. After discussing this with friends, one of them suggested she had general anxiety - her older daughter had the same thing. It made sense. I read some books on relieving your child of anxiety, and used the tips/tricks with her. One suggestion was that it takes 3 to 4 weeks to develop a "habit". So we made a reward chart that was going to take her 3 weeks to complete - and she got a HUGE reward that she had really been wanting if she finished the chart. In the beginning, the first couple of nights, I bent the rules a bit so she wouldn't be discouraged. She wanted that reward so badly, she kept trying. By one and a half weeks, she was getting through the night mostly fine. By the time the chart was finished, she had developed good sleep habits again and had no more anxiety about falling asleep. This may not be at all your son's problem, but consider that there's something else motivating him to need to be near you. At 6 years old, he's old enough to discuss it with you. If it's not anxiety, and the rewards aren't working, I'd move on to punishments. Good luck.