DC1
DC1 is a schedule which logically follows Segmented sleep, shortening its core (usually the second one) and adding a nap to compensate for the lost REM.
Possible variations
Extended sleep cycles
This option is considered standard. It usually has 3h20m first core and 1h40m second core, theoretically making sleep cycles a bit longer (close to 100m). In fact, according to EEG readings of some community members, sometimes cycle lenght might be unchanged and shorter, so there is more LNREM inserted in the end of cores.[1][2]
Standard sleep cycles
This variation is rarely used and has a lower success rate since cores contain less light sleep/REM. It is considered more difficult than the standard one, and usually fits people with lower natural monophasic sleep baseline, about 6-7 hours or less.
Equal core length
Both cores are of the same length. This variation is viable, but rare. It is also considered more difficult than the standard one, since requires sleep cycle compression.
Swapped cores
In this variation the first core is swapped with the second one. The difficulty is also higher, because of the possible SWS wakes and the need for SWS splitting, which is easier for either experienced polyphasic sleepers or those with lower SWS sleep requirements.
Extended
The easiest and a popular option, which has several variations. Usually 3h+3h or 4.5h+1.5h core versions are used, but other options are also possible (e.g. 1.5h+4.5h or 3.5h+3.5h). It usually has 4 cycles instead of 3 (5 or more is also possible, but almost never is used). This variation fits adolescents or those with higher sleep requirements.
Shortened
This option has only 2 sleep cycles, for example 1.5h+1.5h or 2h+2h. Is much harder and recommended only for those with lower sleep needs, 6h mono or less. It allows for much less LNREM/REM.
