Atenolol is a "selective" beta blocker and little to none of it should affect the brain (such as nightmares which are associated with some beta blockers).
Beta blockers main influence on the heart is to lower heart rate not increase it. It also lowers blood pressure and these can result in fatigue as an unwanted side-effect.
Anxiety, I thing not.
Look forward to your family returning home. Sure that will be a big help.
I would not think 1 pill would have that profound an affect on you. I suspect them being away has thrown your energy off and put you in a bit of fear but just for clarification what you are feeling? Anything in particular like your heart jumping around or if it is fast how fast? Any other symptoms beyond just feeling anxious?
By the way the anxiety is been going on for about 5 days