Daylight savings time
A transition to or from daylight savings time (DST) in spring and autumn can adversely affect an adaptation to polyphasic sleep. It is best to avoid attempting to adapt, especially to difficult schedules, if a DST transition will occur soon (within one month or so).
The best way to deal with a DST transition is to change your schedule times accordingly to maintain your original sleep times. For example, after a spring DST transition, you can move all of your sleep times forward by one hour so that all of your sleeps remains consistent with the schedule. This would not set back your adaptation.
If that is not possible, you should aim to change the sleep times cold turkey, wherein you simply switch all of your sleep times on the day of the transition. Note that you should keep your cores and naps to the same length. During the winter transition, it is important that you do not accidentally oversleep your core due to the delayed alarm.
Some users have attempted to transition to DST gradually, e.g., move sleeps by 5 minutes per day over 12 days. However, most of them reported significant tiredness, even more so compared to simply switching cold turkey. It is therefore not recommended to transition gradually.