Racing heart rate in the morning

I am 22 year old female with a history of anxiety which is currently under control, I see a cardiologist for palpitations, He prescribed metoprolol 25mg once a day.  I notice however that as soon as I get out of bed in the morning that my heart rate increased into the 140's for no apparent reason.  If I hold my breath it stops or if I sit down it stops and then slows down into the 70's which is normal for me. After I take the metoprolol in the a.m. I seem to have no other symptoms for the rest of the day.  Is this rapid heart rate a normal thing in the morning as soon as I get out of bed? Does anyone else experience this? I feel if these little episoded were out of the way I could stop the metoprolol all together since I am on a nothing dose of it anyway.

[medops]

Hi have you ever heard of pots, postural orthostatic hypotension syndrome , look it up then go see your doctor. do you excersise? what is your level of daily activity and foremost what is your resting bp in morning hours? there are baroreceptors in your carotids that trigger this response to get more blood to the brain, your heart will beat faster , a healthy resting heart rate is between 60 and 80, it can be normal for faster rates in the morning, i too get these symptoms you are talking about, again i am not a doctor so go see yours, get an ecg and full metabolic panel, these can aid in diagnosis.