Good Morning India:Good Luck, Omar Abdullah

Media Pulse

Professor Gordon McVie and Dr. John Hansen of the Institute of Cancer Epidemiology in Copenhagen studied the medical and employment records of 7,035 women between the ages of 35 and 54 who had been diagnosed with breast cancer. They found that these women, whose work involved night shifts, were 1.5 times more likely than daytime workers to be diagnosed with breast cancer. Dr. Hansen found that the longer a woman worked regularly at night, the higher was her risk of developing the disease.

Although the reasons for this are unclear, one theory is that the risk is increased by exposure to bright artificial light. It is believed that artificial light acts to suppress the production of a hormone called melatonin, which is normally produced in the body at night. This theory is backed by Dr. Hansen’s study of blind women. He found that blind women do not generally suffer from breast cancer. As these blind women cannot sense light visually, it has no impact on their melatonin production.

Scientists from Sweden, too, had found that blind women had a much lower risk of breast cancer. Research, therefore, has suggested that low levels of melatonin may either stimulate the growth of cancerous cells in the breast, or encourage the production of the female sex hormone estrogen, which has been widely linked to breast cancer.

Dr. Richard Stevens, cancer epidemiologist at the University of Connecticut Health Centre, U. S. A., also feels that exposure to high levels of light at night may be linked to an increased risk of breast cancer. He also believes that bright light disrupts basic body rhythms and may suppress the production of hormones such as melatonin. Melatonin is the only hormone secreted by the pineal gland. The pineal gland is a tiny endocrine gland situated at the centre of the brain.

Dr. Aaron B. Lerner and other researchers at Yale University, U. S. A, discovered melatonin in 1958. Melatonin is produced in humans, other mammals, birds, reptiles and amphibians. It is present in very small amounts in the human body. The function of melatonin in mammals remained uncertain until discoveries in the 1970s and 1980s suggested that it regulates both sleeping cycles and the hormonal changes that usher in sexual maturity during adolescence.

The pineal gland’s production of melatonin varies both with the time of day and with age. The production of melatonin is dramatically increased during the night time hours and falls off during the day. Levels of melatonin are much higher in children under age seven than in adolescents and are still lower in adults.

Melatonin apparently acts to keep a child’s body from undergoing sexual maturation, since sex hormones such as luteotropin, which play a role in the development of sexual organs, emerge only after melatonin levels have declined. This hypothesis is supported by the fact that children with tumours of the pineal gland often reach sexual maturity unusually early in life; presumably because the pineal’s production of melatonin has been hampered. Melatonin also seems to play an important role in regulating sleeping cycles. Test subjects injected with the hormone become sleepy, suggesting that the increased production of melatonin coincident with nightfall acts as a fundamental mechanism for making people sleepy. However, Professor Gorden McVie, Director General of the Cancer Research Campaign, U. K., feels that the study is completely inconclusive, and the increased risk is not enormous. Yet it is important and should not be ignored.

Another study carried out by Dr. Ichiro Kawachi, assistant professor of medicine, Harvard Medical School, suggests that working in rotating shifts may be hazardous to women’s hearts. This study focused on nurses, because nursing is one of the professions in which a large number of women work in night shifts.

Around 10 per cent of people are left-handed and that is common to every society and culture over the globe. And everywhere more men are left-handed than women. It has, however, to be remembered that right-handedness is a genetically fixed trait in human beings. This is something unique to Homo sapiens. All other mammals—dogs, cats, rats—seem to be equally split between right and left paw users. What makes a certain percentage of every population left-handed? Despite much research on the subject, no fully convincing explanation is forthcoming. Surveys show that if your mother was left-handed, your chances of being left-handed were approximately doubled. Evidently, all left-handedness cannot be traced to inheritance. Even identical twins sometimes do not share common hand preference. Hand preference becomes well established between three and six years of age.

Even with languages with a right-to-left script such as Persian or Urdu, the curve of letters favours the right hand. A commonplace school item like the ruler has a bias. For the ease of the right-handed user, the numbers are lower on the left and increase as you move right—thus facilitating line-drawing from zero to the length required.