For the most comfortable reach, aim for a nightstand that sits 5-10 cm below...

https://www.apu-bookmarks.win/the-sweet-spot-for-your-nightstand-is-sitting-roughly-5-to-10-cm-below-the-top

For the most comfortable reach, aim for a nightstand that sits 5-10 cm below the top of your mattress. Most standard beds work best with a table height between 55 and 70 cm. Measure your bed while the bedding is on, as that extra thickness matters