anxiety
"Might try this one again someday.  Was on it 3 weeks.  Sleep started off OK but got worse with time along with feeling more anxious and exhausted each day.  3rd week, I'm lying in bed and start to panic.  Try to get up and collapse on the floor.  My brain felt like it was being lightly electrocuted.  Broken sleep and nightmares the rest of the night.  Next day around 3pm, I started to feel better.  Great even and slept great that night but the night before freaked me out so much I swore to never take it again.  Withdrawals were horrific.  Worst thing I ever experienced.  Still, that one day and night was amazing and think it might have been the one if I stuck it out another day or 2.  Weird reactions, I know.  It works great for my dad."