5 CFR §551.432

1. (a)Except as provided in paragraph (b) of this section, bona fide sleep time that fulfills the following conditions shall not be considered hours of work if:
   1. (1)The work shift is 24 hours or more;
   2. (2)During such time there are adequate facilities such that an employee may usually enjoy an uninterrupted period of sleep; and
   3. (3)There are at least 5 hours available for such time during the sleep period.
2. (b)For employees engaged in law enforcement or fire protection activities who receive annual premium pay under 5 U.S.C. 5545(c)(1) or (2), the requirements of paragraph (a) of this section apply, except that on-duty sleep time may be excluded from hours of work only if the work shift is more than 24 hours.
3. (c)The total amount of bona fide sleep and meal time that may be excluded from hours of work may not exceed 8 hours in a 24-hour period.
4. (d)If sleep time is interrupted by a call to duty, the time spent on duty is considered hours of work.
5. (e)On-duty sleep and meal time during regularly scheduled hours for which standby duty premium pay under 5 U.S.C. 5545(c)(1) is payable may not be excluded from hours of work.
6. (f)For firefighters compensated under 5 U.S.C. 5545b, on-duty sleep and meal time may not be excluded from hours of work.