What causes panic attacks at night?

Physical causes: What comes to mind is a problem with shortness of breath associated with lying flat on one's back. If you try propping up your head on several pillows, and your "spells" improve, this is likely the problem. You should see a physician for further evaluation for something called orthopnea.

Panic: One theory is that late in the day when you are less physically active while your brain is still producing adrenaline (anxiety chemical), you can be more prone to get anxious, plus it coincides with the time when people normally are thinking about the events of the day instead of distracting themselves with physical activity.