Is this level of Heartbeat variation - 'normal' ?

[isthereaway]

Is a variation in heartbeat (@ age 20) between low 50's &, occasionally high 130's 'normal'? Mostly around 100-110.
It's worse lying down, worse on waking & last thing at night, worse upon exertion, but still a problem right through the day (variation is temporary)

It will stay around 100/10 for about 10/15 mins, then, for periods of around 2/3mins it jumps up really high, goes down quite low (to parameters in post above) then returns to 100/10 again.

No - that's not normal .

Anything more than 100 per min is tachycardiac - as it doesn't sound like this is related to exercise?

I would make an urgent doctor's appointment.

@leafybrew - it's the variation too that worries me. This is using a brand new fitbit 3 to measure - I don't know how reliable they are, but I can feel pulse is fast just by the wrist.

Bump

Today mine has varied between 74 & 128. The higher spikes are down to climbing the stairs or walking up a hill as I haven't done any exercise today. I am about 20 years older than you.

Your range is definitely not normal. I think wrist watches are known to be a bit inaccurate but I would want to check it out with my GP sooner rather than later if I were you.
Can you manually check your pulse when your watch says your heart is racing just to compare? Do you feel ok when it is over 100?