Tears don't always mean sadness. I suffer from an extremely high "water table." My eyes tend to leak when I receive a phone call from one of my daughters, when the mail comes, when a hallmark commercial is shown and whenever the mood strikes me.
Tears can be both cathartic and refreshing. I'm not a big fan of the "all out sob", especially at bed time because mostly it just causes me to wake with a headache and very puffy eyes.
The best tears are probably the ones you experience about the same time you want to "pee" your pants from laughing so hard. Tears show the humanity in all of us. We share our tears when someone gets bad news, it's a sign of empathy and understanding. Tears can indicate frustration, when no matter how hard you try, things just are not coming together the way you would like.
Tears can indicate need, anger, even hunger, depending on the day. The best thing about tears? They almost always net you a hug. And if we spent more time hugging, more would be right with the world.