Of all the bedroom feng shui rules, this one has the most practical backing. A mirror pointed at your bed reflects light and movement back at you all night, and most people who sleep opposite one report lighter, more interrupted sleep without ever linking it to the mirror.
During the night you half-wake several times. If the first thing registering in that half-awake state is movement in a mirror, your body stays slightly alert instead of dropping back into deep sleep. You rarely remember it, but the sleep quality cost is real.
There is also the simple light issue. A mirror doubles any light in the room - streetlight, a phone screen, a hallway light leaking under the door.
A mirror is the obvious reflective surface, but it is rarely the only one. A switched-off television is a large black reflector. Glossy wardrobe doors, glass wardrobe panels, metal picture frames and even a tablet propped on the nightstand all reflect.
Test it directly: lie in bed at night, then sweep a torch slowly around the room from roughly pillow height. Any surface that catches the light counts.
Cover it at night. A throw, a curtain rod with fabric, or removable frosted film. This alone resolves most cases.
Move it. If the mirror is free-standing, turn it to face a wall or move it inside a wardrobe.
Use wardrobe-door mirrors. A mirror mounted on the inside of a wardrobe door is used when the door is open and hidden when it is shut - the cleanest solution for small rooms.
Reposition the bed. Only if the above are impossible. In rentals and small bedrooms this is usually the last resort, not the first.
An en-suite bathroom with the door left open adds a second reflective surface pointing at the bed. Handle the door first - keep it closed, or hang a curtain - before spending money on the mirror itself.
Size matters less than position. A small mirror directly in your sightline from the pillow is worse than a large one behind you.
Yes, and it is the cheapest fix. Anything that blocks the reflection works - the feng shui concern is the reflection, not the object.
No. A mirror that does not face the bed is fine. Most wardrobes with inside-door mirrors are completely unproblematic.