It was one of eight countries surveyed for the annual global relaxation report, which was released last week, and it was in seventh place in terms of the sleep deprivation rate, with only Indonesia faring better.

The study, done by international premium cruise line Princess Cruises in collaboration with U.S. market research consultancy Wakefield Research, polled 1,000 people aged 18 or above each in the U.S., the U.K., Australia, China, Indonesia, Singapore, Vietnam, and Mexico.

The U.K. topped the list with 66 percent suffering from inadequate sleep, followed by Singapore (61 percent), Australia (59 percent), the U.S. (53 percent), China (51 percent), and Mexico (44 percent).

In Indonesia, 35 percent said they were sleep deprived.

They study also found poor pre-sleep habits among Vietnamese like consuming snacks or drinks before going to bed. The most common pre-bedtime food for Vietnamese is hot non-caffeinated drinks (30 percent), followed by something sweet such as cookies or cakes (21 percent), hot caffeinated drinks (16 percent), chocolate (14 percent), and alcohol (9 percent).

The report also said Vietnamese take an average of 10 days off per year just to catch up on sleep, the same number as in China and Mexico.

They were nine days in Indonesia, eight in Singapore, seven in Australia and the U.S., and four in the U.K.

Not getting enough sleep can double the chances of dying from heart disease or stroke, particularly in people with risk factors like diabetes, obesity, high blood pressure and cholesterol, researchers said.

People in Vietnam sleep on average less than seven hours a day, and are among those who sleep the least across the world, according to a study published last year by U.K. magazine The Economist.

The U.S. National Sleep Foundation warns that sleeping for less than seven hours a night can reduce reasoning and reaction times, and increase the chance of an early death by 13 percent if done consistently.