The golden rule for bedside tables is keeping the top surface between 5 and 10...

https://www.livebinders.com/b/3703999?tabid=ab46b24e-973f-6425-f369-ea1068a28f75

The golden rule for bedside tables is keeping the top surface between 5 and 10 centimetres below your mattress top. This makes reaching for your phone or a glass of water feel natural rather than a stretch