The U.S. and much of Canada will move to daylight-saving time from standard time on Sunday, when clocks will be moved forward by one hour. In the U.S., the Eastern time zone will be four hours behind GMT, the Central time zone will be five hours behind GMT, the Mountain time zone six hours and the Pacific time zone seven hours behind GMT.

In Canada, Newfoundland will move forward an hour to two and a half hours behind GMT. New Brunswick and Nova Scotia will be three hours behind GMT. aylight saving time (DST; also summer time in British English—see Terminology) is the practice of advancing clocks so that afternoons have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn.[1Although not punctual in the modern sense, ancient civilizations adjusted daily schedules to the sun more flexibly than modern DST does, often dividing daylight into twelve equal hours regardless of day length, so that each daylight hour was longer during summer.[12] For example, Roman water clocks had different scales for different months of the year: at Rome's latitude the third hour from sunrise, hora tertia, started by modern standards at 09:02 solar time and lasted 44 minutes at the winter solstice, but at the summer solstice it started at 06:58 and lasted 75 minutes.Modern DST was first proposed by the New Zealand entomologist George Vernon Hudson, whose shift-work job gave him leisure time to collect insects, and made him aware of the value of after-hours daylight.