Patient with disturbed sleep often also complain of overall lethargy throughout the day. This is because they could not sleep properly in the night and wake up feeling very tired. This also affects their productivity during the day as they could not give their best. 25% of your total sleep should be REM sleep. But patients with OSA would not achieve even 10% REM. Their sleep quantity may be constant but quality is poor. It is carried over to the next day.