Doxylamine
insomnia
"I have had insomnia since a hysterectomy in 2009, so began taking benadryl but that had the opposite effect on me & I became very jittery w/ "restless leg syndrome", so tried Unisom 25mg nightly.  I have been taking Unisom now for 6 years and it has worked pretty well to help me sleep at night.  However, 2 months ago I developed a fast & irregular heart rhythm.  I am a nurse, so listened to my heart and could hear the missed beats when I felt them.  It felt like I had just ran up a flight of stairs but I wasn't out of breath.  My heart was just beating very rapidly and irregular.  Couldn't figure out why I was having palpitations so quit taking & saw Dr. Diminished palpitations since I quit taking & all my heart tests and labs are normal."