(Reuters) - Two-thirds of Americans drink coffee, and many gulp down their first cup within an hour of awakening, according to a survey released on Thursday.

On average, the 65 percent of Americans who drink coffee each consume an average of 13 cups of coffee per week, and three out of five agreed with the statement "I need a cup of coffee to start my day."

Timed to coincide with "National Coffee Day" next Thursday, September 29, this month's survey of 1,009 Americans, which had a margin of error of 3 percentage points, was commissioned by the 7-Eleven chain of convenience stores. The stores will be giving out free coffee that day from 7-11 am.

Among the findings, 28 percent of coffee drinkers had their first cup within 15 minutes of waking up and 68 percent within an hour, 57 percent added sugar or sweetener to their brew, and 54 percent agreed that "coffee makes me feel more like myself."

(Reporting by Andrew Stern; Editing by Jerry Norton)

(This Thursday story was corrected in paragraph three to change the day and time of the event on Sept. 29)

Mochila insert follows.