Modern space flight has always had the convenience of artificial gravity. Most people today have never experienced zero g weightlessness, even with many parsecs of space travel under their belts. Though gravity systems do fail on occasion, this time it happened to you!
About two weeks from arriving back on Earth, you were feeling confident and went to bed without your tether and just a sheet, no clothing at all. The tether was supposed to keep you from hurting yourself, if artificial gravity was ever be lost while you were asleep.