I like SuperNanny's method. First time the babyis out of bed quietly and calmly take her back to bed telling her that you expect him/her to stay in bed. Then sit on the floor where you can stop them when they get out of bed and calmly take them back to bed only from now don't say anything. Even if they fight, cry, scream put them back to bed calmly. Then go back to your post. I think you can be sitting in the bedroom but not at bedside.
This is difficult to do, especially when you have to pull an all nighter but in the long run you will get more sleep.
In the TV presentation the mother had to do this nearly all of the first night. The time doing this each night shortened. In a week or so the toddler was staying in bed all night most nights. The parents were to not relent and take her back into their bed.
My daughter was having the same difficulty with her son who was perhaps a bit older than your son and her daughter who was in Kindergarten. She stayed up watching TV and everytime they got out of bed she took them back to bed. She did lecture them and perhaps that's why it took her several weeks before she could just tell them to go back to bed and not have to take them. During the last couple of years they usually stay in bed once they're there.
The kids do have a night light and a CD playing their choice in music. I was surprised that a couple of the CDs were not soothing but they still went to sleep at the same pace as when the lullabyes were playing. The volume is low.
We also tried different methods but neither of us was consistent with ourselves or the other. I've found that one has to consistently do the same thing over and over and over before the baby accepts that boundary. Because they are learning to be more independant and because their brain is very immature they test the same boundary over and over and over. The boundary we're teaching is learned more quickly when they get the same result every time. Pavlov tested this theory using a dog. The same thing over and over while remaining calm but firm. Probably not so difficult with Pavlov but definitely trying for parents.
I also agree that quiet time usually has good results. The baby is rested without sleeping. Both of my grandchildren gave up naps early. they had an hour of quiet time every afternoon. I think they kept the morning naps.
Since my grandson has been with his current caretaker (at least a year) he has returned to taking afternoon naps. Each child has their place to sleep. For awhile Chase was choosing the carpeted floor. And they were expected to be quiet. They had to stay lying down. If the child had difficulty staying down they slept in a "playpen." (Can't remember the current noun) That way they had a defininte boundary. Chase chose to sleep in the "playpen" for awhile. The caretaker has several; so several children could sleep within a prescribed space. He even has afternoon naps at home now. He would never nap at my house but when I say nap time now he takes my hand and easily goes to sleep. He's almost 5.
Calm consistency! This caretaker is unflappable.
About melatonin. I've tried melatonin and valeerian and neither one helped me sleep. I purchased them in the Health Food section at Fred Meyer. The label only gives directions for adults. They are an aid for some adults. I wouldn't give a baby either of these without consulting a doctor. A naturopath would be probably be more knowledgeable. They might be able to answer this over the phone. I found that one of the natural food stores, such as Natures or New Season's, had a naturopath working in the supplement section a day or so a week. A couple of years ago I asked her for advice. I don't know if the store still does that.