Many–if not most–regions of the world use daylight saving time (summer time) for about half a year. For example, Eastern Standard Time (EST), which is Greenwich Mean Time (GMT) minus 5 hours (GMT-5:00), becomes Eastern Daylight Time (EDT), which is GMT minus 4 hours (GMT-4:00); and the time in Western Europe (e.g., Zurich) goes from GMT+1:00 to GMT+2:00.
When creating a Doodle poll, the poll creator can set a time zone so that the times she chooses for the poll options are with respect to that time zone. However, Doodle seems to only offer time zones for winter time. For example, “(GMT-5:00) EST” is available, but “(GMT-4:00) EDT” seems not to be; “(GMT+1:00) Zurich” is available, but “(GMT+2:00) Zurich” seems not to be. Furthermore, a poll’s options might feature both dates that lie in winter time and dates that lie in summer time.
So what are poll creators and poll participants supposed to do? First and foremost, don’t worry! Simply choose the “normal” time zone for your region without concern for the current time or the dates & times of the respective poll. For example, a user in New York always chooses “(GMT-5:00) EST” while a user in Zurich always chooses “(GMT+1:00) Zurich”. Behind the curtain, Doodle (or rather the Java platform that Doodle is based on) does its summer-time magic if need be.
Here’s an example: http://doodle.com/ehbn7guem4tq4m4f. A company with an office in New York and an office in Zurich wants all employees to be on a conference call. An employee from the New York office sets a Doodle poll up, always suggesting 9 to 11 AM.
Most of the year, the time difference between New York and Zurich is 6 hours (GMT-5 -> GMT+1 or GMT-4 -> GMT+2), so 9 to 11 AM typically becomes 3 to 5 PM. However, daylight saving time begins one week earlier in New York and ends one week later, so for two weeks per year, the time difference is only 5 hours (GMT-4 -> GMT+1) and 9 to 10 AM becomes 2 to 4 PM during those two weeks (cf. March 11 and 13 as well as October 28 and 30).
None of the users has to worry about that, either, as Doodle takes care of any and all necessary conversions. And everybody is on the same call at the right time!