Experts think this is because eating releases a rush of stress hormones when the body should be starting to relax.
People who do not see their blood pressure fall at night are known as 'non-dippers' - and have a much higher rate of heart-related death.
Late eaters were nearly three times more likely to be non-dippers, the Turkish researchers found.
Researcher Dr Ebru Özpelit, presenting her results at the speaking at the European Society of Cardiology congress in Rome, said: 'If we eat late at night, the body essentially remains on high alert as during the day, rather than relaxing for sleep.
"Stress hormones are secreted, causing blood pressure not to decrease during sleep, which should normally happen."
Dr Özpelit, from Dokuz Eylül University in Turkey, tracked 721 on people diagnosed with high blood pressure, with an average age of 53.
She found that those who ate within two hours of going to bed were 2.8 times more likely to retain high blood pressure overnight.
Some 9.4 million people in the UK are diagnosed with high blood pressure, which is also known as hypertension.
They are already at a higher risk of heart disease, but if their blood pressure does not fall at night, that risk increases to a far higher level.
Experts estimate that 40 per cent of patients with hypertension are non-dippers - potentially 3.76 million people in Britain - putting them at serious risk of major heart problems.
Dr Özpelit said: "It is more dangerous. If blood pressure doesn't drop by more than 10 per cent this increases cardiovascular risk and these patients have more heart attacks, strokes and chronic disease."
But even healthy people with normal blood pressure should take note of the findings, Dr Özpelit said.
"How we eat may be as important as what we eat," she said.
She advised that people do not skip breakfast, eat lunch, and keep dinner to a small meal.
"Eating breakfast and lunch is important but dinner must not be later than seven o'clock in the evening," she said.
The findings add to a growing body of evidence which suggests keeping all meals to within a fixed period of time - and fasting at night - can have a wide range of health benefits.
Previous research has found that an early dinner reduces the risk of breast cancer, lowers blood sugar levels, and helps burn off calories.
Experts think part of the reason is that the body evolved to expect meals much earlier in the day - because people went to sleep when it got dark.
Dr Özpelit said the invention of electricity changed that - introducing "erratic" eating patterns.
"With the advent of affordable artificial lighting and industrialization, modern humans began to experience prolonged hours of illumination every day and resultant extended consumption of food," she said.
"Late night eating and skipping breakfast is such an erratic eating pattern which is becoming more prevalent day by day."
Professor Peter Weissberg, medical director of the British Heart Foundation, said: "This research suggests that eating a meal late at night may contribute to the failure of their blood pressure to reduce.
"It is normal for blood pressure to reduce overnight, even in people with high blood pressure.
"However, in some their blood pressure remains elevated throughout the night putting them at potentially higher risk of future complications."
