The survey of more than 1,000 children who sat key stage two tests last year found eight smoked on the morning of their tests, while 37 ate chocolate, 30 had high-sugar drinks, 45 had biscuits, 19 had crisps and nine had a pasty or sausage roll.
The poll by market research company Opinion Matters found 55% feared bad results would affect their future and more than two thirds (68%) admitted feeling pressured at exam time.
A second piece of research of 1,000 parents also found that 20% believed their child was too nervous to eat before SATs exams, while one in eight parents said their child had refused food.
Some 22% of children reported losing sleep during their SATs, but the figure rose to 59% among children who admitted skipping breakfast.
The surveys, which were commissioned by Kellogg’s, also found that children reported not being able to concentrate due to being nervous (20%), not being able to eat because of nerves (12%) and feeling hungry due to skipping a meal (14%).
Kellogg’s is donating 44,500 breakfasts to 300 school Breakfast Clubs this week so children taking their SATs won’t sit their exams on an empty stomach.
Paul Wheeler, Kellogg’s director, said: “This is the third year that Kellogg’s has donated extra food to schools during SATs week.
“We’re sorry to hear that children are feeling stressed and hungry before their exams, so we hope that by attending school breakfast clubs they’ll get the boost they need to do their best.”
John Coe of the National Association for Primary Education said: “A decent breakfast should set children up for success in their exams, and eating breakfast with friends at a Breakfast Club - and calming each other’s nerves about the tests - is a happy way of meeting the challenge to come.”
Year six pupils across England will sit their key stage two SATs this week.