One of the main challenges of the space development program has been giving astronauts the same level of physiological and mental comforts they get back at home. However at 400 km altitude and confined to a small aluminum can this becomes a daunting task.
Generally astronauts zip themselves inside vertical sleeping bags. They leave their arms outside and use a strap that circles the waist. Each sleeping compartment has a light for reading and side panels that can be shut for privacy.
However just like on earth the sleep patterns differ among astronauts. Many astronauts have no trouble sleeping. Approximately 50% of the astronauts complain of sleep disruption patterns.
Many astronauts, including Canada's first astronaut Marc Garneau, preferred to sleep "free floating". He was known to simply curl in the corner and doze off….