Sleep Restriction Therapy (SR). The initial Time in Bed (TIB) prescription is calculated on the average total sleep time (TST) reported in the baseline sleep logs. After one week, depending on subject's daily sleep logs, the therapist suggests a new TIB prescription. Napping is neither prescribed nor proscribed. However, if subjects find themselves very sleepy (not just tired, but actually sleepy) they are advised to take a brief (15 to 30 minutes) nap to ensure their safety.