Hold off until tomorrow to have it out with your sister about that annoying comment she made. Instead of feeling cathartic, it's probably going to rile you up, and your churning mind will continue to keep you awake into the wee hours. Stress and overstimulation before bed are said to be the main causes of delayed sleeplessness, or "parasomnia."
Declare the hour before bed to be your peaceful period, and avoid conversations that will rattle you.
Next: What the sleep experts do to get a good night's rest