Arduino for STM32

I read a sensor every 10 ms by using an interrupt and do other stuff afterward with Arduino. I use the following while loop and fill-up an array while waiting inside the loop and exit the loop as soon as the array gets full.
I would like to keep a Nucleo L476 to do the same task with the minimum consumption power.
This loop takes a few seconds to be terminated. Is the sleep mode efficient in such cases? How to apply that here?

Many thanks for your guidance!

Thank you so much!
I implemented sleep mode and work further around this loop-case to find a better solution with less sleep-wake up procedure. With 1 ms sleep time, it has to sleep and wake up ten times during each 10ms interrupt time. I increased sleep time to 10 ms instead of 1 ms to get better performance.
Since the loop time varies and runs up to 10 seconds, is there any other way to get the lowest possible power consumption during this loop time?