Too much of anything is not balanced or healthy. Letting tears flow is healthy, but don't cling to the tears, release and let go of the emotion. Pleasant, painful, or something else, too much is unhealthy.
Crying every night before sleep is abnormal, I hate to say it.
Let's ask Doc Wilson,
'Crying can be an extremely useful and necessary method for releasing acute sadness, primarily, and perhaps some anxiety related to sadness. It is a natural body function, in fact. Babies and children use it spontaneously. Adults often have been trained not to use it, or have literally forgotten how good it can feel and how therapeutic it can be in some situations.
Tears also contain certain chemicals and may be a way the body eliminates some toxins. The fact that tears flow from the eyes, which are near the brain, is important and has to do with the release of sadness, primarily.'
Too much can deplete nutrients,
http://drlwilson.com/ARTICLES/CRYING.htm
DrGonzos 2 cents:
"Tears do for the soul what rain does for flowers."
Thought I would explain this a bit. Basically, it's fine. It would help your soul grow but like if you water a plant/flower too much, you'll kill it.
Crying isn't a sign of weakness, but crying all the time can be a sign that you have a deep emotional issue that needs resolving. If anything not crying is unhealthy as it shows that you are not expression your emotions.