Random Burst of Energy

I’m currently 35w6d & this is my first pregnancy. Usually I’m super worn out and tired all the time but tonight for some reason I just feel super restless, I haven’t been able to lay still in bed so I keep getting up and walking around and going up and down the stairs. I’ve never experienced this before, my SO keeps telling me to lay down but my body and legs just keep wanting to get up and move. Sounds funny but I’m honestly baffled by what’s going on... has anybody else ever had this happen before? Or know what the cause of it could be? I should be sleeping but I can’t because I’m wide awake and I’m going nuts 😩