The extended version is the usual recommendation for sleepers who are younger than 16 years old, or people who have a highly physically active lifestyle, a high sleep requirement and/or scheduling constraints (e.g, long wake gap from 9 AM to 5 PM). For a 9-hour monophasic sleeper, this variant offers a decent amount of sleep reduction, requiring only one nap. With a lot of sleep in stock, the extended version allows for more versatility in the placement of nap times. Because most, if not all of the vital sleep stages should be covered by the core, the nap mostly serves to give an alertness boost to improve learning and memory. As a result, the nap may be placed in later hours of the day (e.g, 4-5:30 PM).
