Other-standby followed by an FDP CS FTL.1.225(b)(2): How shall an operator expect a crew member to use whole or part of a standby for sleep when there are disturbance factors like difficulty to fall asleep, disturbed sleep due to sick children, waking-up by external noise, etc.?
According to CS FTL.1.225 (b)(2), the operator designs its standby procedures in a certain way. The expectation is on the design of the procedure by the operator, not on the individual crew member.
The expectation on the crew member is to follow the procedure to the best of his/her abilities and in good faith at all times.