To get your bedside table height just right, aim for the top of the nightstand...

https://fionafreshmaids.com/the-ultimate-guide-choosing-the-perfect-bedside-table-height-for-a-65-cm-mattress/

To get your bedside table height just right, aim for the top of the nightstand to sit roughly 5 to 10 cm below your mattress surface. This creates a comfortable reach when you are in bed