For the best look and easy access, your bedside table should sit 5-10 cm below...

https://jasperotbu571.iamarrows.com/the-ergonomic-guide-optimising-nightstand-height-for-limited-shoulder-mobility

For the best look and easy access, your bedside table should sit 5-10 cm below the top of your mattress. This setup feels natural when you reach for a glass of water or your phone at night. Most standard tables in the UK range from 55-70 cm high