>>2 >>3 >>4

So, let me rephrase this:

You are locked into an empty room. It's empty. The wall are white-painted drywall. The floor is covered in a soft apple green carpet and completely stainless.

There is a single, purposely-designed luminaire on the lavender-coloured ceiling. The lamp is cycled through different colour schemes to simulate night and day. The ceiling is unreachable to you, even if you jump. The only visible feature, apart from the luminaire, are openings for ventilation. The room temperature is strictly regulated to 72.5°F.

There is no outside noise. After about an hour you begin to shout and notice that the walls must be designed to muffle and sound.

You are left in the room for two days - at least this is what you believe.