1. Noise: If people often walk in stairwells or passages, it may produce some noise, thus affecting the quality of sleep. If you are sensitive to noise, you may need to consider placing some sound insulation materials at the bedside, such as thick curtains or sound insulation boards.
2. Safety: If the bedside is against the wall, and behind the wall is a passage or stairwell, some safety problems may occur. For example, you may get out of bed accidentally because you are unstable against the wall, or get out of balance when you get up. Therefore, you may need to consider putting some protective measures at the bedside, such as installing guardrails, or using thick pillows and cushions to increase the stability when leaning against the wall.
3. Privacy: If the bedside is against the wall and behind the wall is a passage or stairwell, your privacy may be affected to some extent. Others may see your room and bed from the passage or stairwell. If you are very concerned about privacy, you may need to consider installing curtains or shades in your room to protect your privacy.
In short, behind the wall of the bed are passages and stairwells, which may have some effects, but these effects can be alleviated by some measures. You can decide whether you need to take measures according to your own needs and circumstances.