Changes in Routine
There are certain behaviors that, for most people, typically stay within a baseline range. Things like eating, sleeping and personal-hygiene practices tend not to vary dramatically day to day or week to week within a single stage of life.
If you notice your teen is suddenly sleeping much more or much less than usual, eating much more or much less than usual, neglecting basic hygiene like washing up and putting on clean clothes or showing a complete lack of interest in personal appearance, be on alert. These changes can indicate a mental disturbance that requires attention.
Finally, the most clear (but often ignored) indicator of suicidal thoughts …