Not good. This matter can be understood from two levels of Feng Shui.
1. Stones at the head of the bed make people feel oppressive and cause psychological discomfort. This is not good. It is said that if something has a form, it must have energy, and this energy has a negative impact on the human body.
2. The stone itself is Yin and comes from nature, so it is easy for Yin energy to accumulate. Placing it at the bedside will allow these negative substances to directly interfere with the human body, which is not good for people.