It's not only during student years that we tend to stay awake long into the night.

Nearly twenty percent of us have to deal with disturbed working patterns at some point in our career.

Several crucial sectors of our socio-economical system ranging from healthcare through military services need shift workers.

Nocturnal light exposure influences production of melatonin - the main hormone responsible for controlling our circadian rhythm. By changing its production, irregular night work stimulates development of sleep disorder and chronic fatigue.

We deal with drowsiness by smoking or eating, with the former keeping us stimulated and the latter helping to readjust our biological clock. 

But the impact of night shift work on our health is greater than what we struggle with every day - alternating work schedules have been classified by the World Health Organization as a probable carcinogen!

The consequences of irregular sleep are detrimental. Recent publication from the American Journal of Preventive Medicine explains the results of a long observation of health changes due to rotating night shift work (meaning minimum three nights per month).

The study was performed on a group of almost seventy-five thousand U.S. nurses.

Dr. Eva Schernhammer, an Associate Professor of Medicine in Harvard Medical School and senior author of the paper says, "We examined overall mortality in these women, and observed significantly higher overall mortality, as well as higher mortality from cardiovascular disease in women with several years of rotating night shift work, compared to nurses who had never worked night shifts."

Are the consequences of night shift work on a regular schedule and rotating night shifts different? "Anything that challenges our biologic clock constantly (like rotating between sleeping at night and during the day) would be more detrimental than regularity (i.e. permanent night work)", said Dr. Schernhammer and added: "It's sort of like flying between London and New York every three days - constant jet lag."

The numbers leave little space for doubts. Women who worked night shifts for more than six years had higher risk of cancer and cardiovascular disease mortality than those who never worked at night.

For those who worked shifts for more than fifteen years, the highest risk was associated with lung and colorectal cancer, with the former resulting mainly from smoking. The main cardiovascular problem identified in this group was ischemic heart disease.

Different patterns were observed for the nurses who worked shifts for less than five years.  This group had elevated numbers of mortality cases related to various cardiovascular diseases (that were coupled with current or former smoker status) and higher number of deaths resulting from lung, breast and pancreatic cancer.

Sounds very serious, doesn't it? When asked for remedial measures for shift workers, Dr Schernhammer replied, "For now, night workers may just try to eliminate as many other lifestyle-related risk factors as possible, e.g. quit smoking, exercise regularly, eat healthily, maintain a healthy weight, get regular screening."

This study is not the first one to prove the connection between alternate work schedules and cancer development, yet it is a big and a significant one.

The first European cases of receiving governmental compensation for cancer developed as a result of shift work were reported in 2009 in Denmark.

It does not seem like the compensation will be given on a regular basis in the rest of Europe anytime soon, though even if it would, the risks stay exactly the same. So please, rotating shifts workers, take good care of yourself.