For the most comfortable setup, aim for your bedside table to sit roughly 5-10...

https://www.charliebookmarks.win/finding-the-perfect-nightstand-height-is-all-about-comfort-and-reach-aim-for-a

For the most comfortable setup, aim for your bedside table to sit roughly 5-10 cm below the top of your mattress. This makes it easy to reach your phone or a glass of water without straining your arm