I'm dealing with this currently due to mild ongoing sleep-dep. A couple of suggestions. For putting the anxious/panicky emotions into context, I'm going to recommend daily meditation. You might start with Understanding vipassana meditation on this site. For focusing on tasks -- this is the hardest for me. The Pomodoro Technique works for me -- for a while, before it stops working. But it does help me get over productivity slumps from time to time.