For the most practical setup, aim to have your bedside table sit 5 to 10 cm...

https://amumreviews.co.uk/should-bedside-tables-be-higher-than-the-bed/

For the most practical setup, aim to have your bedside table sit 5 to 10 cm below the top of your mattress. This makes reaching for a glass of water or your phone effortless while you are in bed