The same principles that apply to the 3h core also apply to a 3.5h core. The core sleep still should start by 22-23 to retain a sufficient amount of SWS. If all SWS has been accounted for, the additional 30 minutes will provide REM and/or light sleep, which may help with either gaining enough REM or sustaining wakefulness. This is also a core duration that is popularly used in Segmented sleep and scheduled in the SWS peak for the same purpose. The naps should be placed in the same way as the standard schedule.
