usually during sleep basal heart is low comparison to wake condition, what happens when we suddenly wake up , rebound tachycardia
results . Thats a normal body response.
If it is associated with palpitation
or lasting for minutes together or you feel during day time also
then you have to seek medical attention otherwise not
As you are already having POTS,MVP
, extasystoles are common
I think you are satisfied by my answer