Anxiety follows many different cycles, many without rhyme or reason. At times, your anxiety will be worse at night, sometimes worse in the morning, and so on. A lot of it has to do with your past experiences with anxiety. For example, if you've had a few panic attacks at night, you will be more anxious at night, anticipating a repeat occurence.
No matter what tiime of the day you feel more anxious, you need to employ any coping mechanisms you've learned through therapy, and keeping the mind busy will help some too.
Text people if you can.. Cause having no communication at all makes me get all paranoid and worse... TV is the best though. It makes it feel like there's someone there in a way... >.<
It kicks in at night because our mind isnt kept busy and we just sit there in bed and think aaall the time! Listen to music or watch a movie before you fall asleep!