For the most comfortable feel, aim for your nightstand to sit between 5 and 10...

https://lilyluxemaids.com/the-golden-ratio-of-bedside-comfort-matching-your-mattress-to-a-60-63-cm-nightstand/

For the most comfortable feel, aim for your nightstand to sit between 5 and 10 centimetres below the top of your mattress. Most standard bedside tables in the UK range from 55 to 70 centimetres tall