I don't know if there's any better sound than a young child laughing uncontrollably while being tickled. When I was a kid my sister and I tickled my three year old brother relentlessly. He eventually developed a stuttering problem and my grandma believed that the tickling was to blame. She enforced a moratorium on any future tickling while she worked with him on slowing down and sounding out his words. It worked and my brother got through his stuttering phase.
I don't know if the tickling was the cause but now that I am a parent I do notice that I use tickling a great deal with my three year old. It's basically the toddler version of waterboarding. When he's lying on the floor curled up in a ball refusing to get his coat on a good tickle will soften him right up and make him like putty in my hands. Timeouts are still necessary but sometimes instead of threatening or taking something away we can both change the mood in the house, interrupt both of our negative patterns and get a good laugh. With a toddler some days just aren't easy and he as well as myself need a mental reset.
As a chiropractor and dad I'm always interested in how we can stimulate the nervous system and tickling is a massive stimulus to a young child’s nervous system. Neuroscientists tell us that tickling stimulates multiple areas of the brain, particularly the areas that give signals for pleasurable experiences. Research suggests that we have evolved to laugh when tickled to show our submission to an aggressor, to dispel a tense situation and prevent us from getting hurt. I guess in an evolutionary way tickling is my way of showing that I'm still the silverback of the family. Also when he laughs he is building those neural pathways for happiness. Hopefully the more he laughs as a child the more his nervous system is primed for happiness throughout his whole life.
We know that laughing or just smiling instantly changes our physiology for the better. Studies have shown that when a sad person physically forces a smile, their biology changes to a state similar to as if they were emotionally happy. This is one reason I am infatuated with something called laughter yoga. Laughter yoga is where you intentionally force yourself to laugh with a group of people for an hour. No jokes are told, no funny skits are watched, you literally just go through some fun exercises where you laugh. Through the course of the hour the fake laughter becomes genuine laughter and everyone else’s laughter becomes contagious even though you are literally laughing for no reason. Afterwards, the endorphins and bonding hormone oxytocin are surging through your body and you feel strangely close to this room full of strangers you just laughed with.
Athletes have been known to use this effect during moments of extreme exertion. World record freedivers that dive insane depths on one breath of air will crack a small smile as they are ascending which allows them to relax and conserve oxygen as their body is screaming for air. This is also a common technique that is used in yoga as well. When struggling through a difficult asana a tiny smile will often steady shaking and allow you to relax into a pose.
Laughter is good in any shape or form not only for a child but for everyone. In my mind tickling is just another way that we as parents can adjust the nervous system of our kids and set them up to be happy healthy adults.