The golden rule for bedside tables is keeping the top surface within 5 to 10...

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

The golden rule for bedside tables is keeping the top surface within 5 to 10 centimetres below your mattress top. This makes reaching your phone or water effortless while you are lying in bed