Women who work night shifts are at a greater danger of dying from heart disease than those who work day shifts.
In one of the largest studies carried out, scientists discovered that those who worked rotating night shifts for five or more years were at increased risk of death from diseases of the heart or blood vessels.
According to a new study published in the American Journal of Preventive Medicine, people working over 15 years of rotating night shift work had an increased risk of dying from lung cancer.
The World Health Organisation (WHO) classed night shift work as a probable carcinogen (cause of cancer), due to the way it disrupts a person's body clock, or circadian rhythm.
The latest research used data from the Nurses' Health Study that started in 1976, collated information from 121,700 US female nurses aged 30-55, who answered questionnaires every couple of years.
A rotating shift is defined as working at least three nights per month, plus working days or evenings in the same month.
The study found that death from all causes was 11% higher for women who worked over five years. Death from cardiovascular disease was 19% higher for this group.
For lung cancer, there was a 25% higher risk in those who worked night shifts for more than 15 years.
Professor Eva Schernhammer, of Harvard Medical School and the Brigham Women's Hospital in Boston, told the Daily Mail that the study "is one of the largest prospective cohort studies worldwide with a high proportion of rotating night shift workers and long follow-up time.
"These results add to prior evidence of a potentially detrimental relation of rotating night shift work and health and longevity," she added.
Last July, Medical News Today reported on a study associating shift work with increased risk of type 2 diabetes.
Other studies have further demonstrated how the health of night shift work is affected in other areas. Around 30% of shift workers are obese, as opposed to 24% of men and 23% of women who worked normal hours.
Shift workers also had long-term health problems such as back pain.