How does a driver log Daylight Savings Time?

There are no "official" guidelines for logging when the time changes. What most drivers do is simply drop a line down to the remarks section of the log to indicate the time change. So at 02:00 AM, Sunday morning, drop a line down and write something like, "Daylight saving." It should not affect drivers' hours because they still must comply with the 11-, 14- (or 10-, 15-), and 60/70-hour rules. These rules are not dependent on what the clock reads; rather they depend on how much time the person actually worked/drove.
When you "gain" an hour in the fall, your log for that day should include 25 hours of activity, because you repeat the hour from 1:00 a.m. - 2:00 a.m. The log needs to show what you did for that hour, so enter a note indicating your activity and any changes in duty status. That hour must be included when calculating compliance.