Keeping to a regular bedtime could prevent a heart attack or stroke, according to new research.

It is as important for adults as it is children - reducing the risk of obesity, diabetes and cardiovascular disease, say scientists.

A study of almost 2,000 older people found those whose sleep patterns were more erratic weighed more, had higher blood sugar and were more prone to illness.

Their projected risk of having a heart attack or stroke within 10 years was higher than counterparts who slept and woke at the same time every day.

Irregular sleepers were also more likely to report depression and stress, both of which are tied to heart health.

It suggests a person's sleep habits could be used as a screening tool to identify vulnerable individuals - enabling them to be prescribed preventative drugs.

Lead author Professor Jessica Lunsford-Avery, a psychiatrist at Duke University, Durham, North Carolina, said: "Heart disease and diabetes are extremely common in the United States, are extremely costly and also are leading causes of death in this country.

"To the extent we can predict individuals at risk for these diseases, we may be able to prevent or delay their onset."

Britons are among the most sleep deprived in the world, with almost four in ten saying they do not get enough.

The average person gets manages six and a half hours a night, which for most people is not enough.

Sufficient sleep has been proven to help keep the body healthy and the mind sharp. During shut eye the body produces melatonin, a hormone that protects against cell damage.

But the new findings published in Scientific Reports suggest it is not just an issue of getting at least seven hours sleep a night.

Maintaining a regular bed and wake time may be just as vital for heart and metabolic health.

Prof Lunsford-Avery and colleagues followed 1,978 middle aged and elderly participants who wore a device on their wrist, similar to a watch, that tracked their sleep schedules down to the minute.

This enabled them to work out whether even subtle changes - going to bed at 10:10 pm instead of the usual 10 p.m - were linked to the health of the 54 to 93 year old volunteers.

The study also included sleep duration and preferred timing - whether someone was an early to bed early to rise lark or a night owl.

This found people with high blood pressure, that can trigger a heart attack or stroke, tended to sleep more hours. Meanwhile, those with with obesity were more likely to stay up later.

But of all three measures, a regular or irregular bedtime was the most accurate way of predicting someone's heart and metabolic disease risk.

As one might expect, irregular sleepers experienced more sleepiness during the day and were less active -- perhaps because they were tired, Prof Lunsford-Avery said.

Her team plans to conduct more studies over longer periods in hopes of determining how biology causes changes in sleep regularity and vice-versa.

She said: "Perhaps there's something about obesity that disrupts sleep regularity. Or, as some research suggests, perhaps poor sleep interferes with the body's metabolism which can lead to weight gain, and it's a vicious cycle.

"With more research, we hope to understand what's going on biologically, and perhaps then we could say what's coming first or which is the chicken and which is the egg."

Prof Lunsford-Avery said the results show an association - not a cause-and-effect relationship - between sleep regularity and heart and metabolic health.

She added: "From our study, we can't conclude that sleep irregularity results in health risks, or whether health conditions affect sleep. Perhaps all of these things are impacting each other."

African-Americans had the most irregular sleep patterns compared to participants who were white, Chinese-American or Hispanic, the data showed. People with diagnosed sleep disorders such as sleep apnoea were not included.

A host of previous research has linked poor sleep to ill health. Night shift workers, in particular, have been found to be more prone to disease.

One study by the University of Surrey found getting an hour's less sleep a night affected the activity of around 500 genes in volunteers, including some associated with inflammation and diabetes.