The risk of breast cancer or diabetes could be cut if women refrained from night-time snacks, a new study suggests.

Researchers from the University of California, San Diego School of Medicine have discovered that fasting at night is crucial for good health. It is the first study to show that nocturnal eating should be avoided to allow the body's metabolism to work in alignment with natural sleep-wake cycles.

"Increasing the duration of overnight fasting could be a novel strategy to reduce the risk of developing breast cancer," said lead author Catherine Marinac.

"This is a simple dietary change that we believe most women can understand and adopt. It may have a big impact on public health without requiring complicated counting of calories or nutrients."

Eating regularly and waiting longer between dinner and breakfast will regulate blood sugar and lower risk of illness.

For every three hours of extra fasting at night, said the study, women were 20% less likely to have hyperglycemia - or high blood sugar - a known risk factor for breast cancer and diabetes.

The study noted that night shift workers were at a risk of breast cancer as a result of unusual eating patterns.

More than 2,000 women took part in the study and were asked to record their eating and sleeping patterns between 2009 and 2010.

The research was published in the journal Cancer, Epidemiology Biomakers and Prevention.