Heart rate and blood oxygen only on demand and while using workout app

Hello .I am new in using an Apple Watch and I am curious to understand if there is an option to stop the continuous heat rate and blood oxygen and set up only when using the app or training (using workout app).I see that when I am in bed and not moving my arm ,the sensors start to work and measure which lead to unwanted data and battery drop.Can you tell me if there is an option to stop only this metrics while I am not in the move.I want to be able to measure them when I am using the app or training and not to be on all the time and measure every couple of minutes?