in the Dark to Be Healthy
Dr. Ben Kim
night shift workers have a higher risk of developing breast cancer
than the rest of the female population. An interesting study in the
1, 2005 issue of Cancer Research provides new information that
might partly explain why this is.
found that sleeping for several hours in nighttime darkness promotes
a healthy blood level of a hormone called melatonin, which can significantly
suppress the growth and proliferation of breast tumours.
also found that sleeping while exposed to light at night causes a
dramatic drop in blood melatonin levels, setting the stage for growth
and proliferation of breast cancer cells.
study provides evidence that may partly explain why breast cancer
is five times more common in industrialized nations compared to less
developed countries. It may also explain why visually challenged people
have lower rates of cancer than people who have no problems with vision.
are the essential details from this study:
measured tumour growth and melatonin blood levels in rats that
had malignant liver cancer or human breast cancer cells that were
grafted into the rats.
growth and melatonin blood levels were measured in response to
introduction of blood from healthy, premenopausal female volunteers
whose blood was taken:
nighttime following 90 minutes of exposure to white fluorescent
light to their eyes
that were introduced to blood that was low in melatonin (samples
taken during daytime and during nighttime following 90 minutes
of light exposure) showed high proliferative activity.
that were introduced to blood that was high in melatonin (samples
taken during nighttime darkness) showed a significant suppression
in proliferative activity.
brilliant study highlights the importance of getting restful sleep
at night with minimal exposure to light. Doing so is essential to
promoting a healthy circadian cycle, which is needed to produce an
optimal amount of melatonin, as well as other hormones that are beneficial
to health such as growth hormone, testosterone, and erythropoietin.
getting restful night time sleep in darkness and having a high blood
level of melatonin are not the only factors that influence your overall
health status and risk for developing cancer. A clean diet, peace
of mind, appropriate amounts of physical activity, and an unpolluted
environment are also essential requirements for your best health.
have family members or friends who sleep with a light on (or have
their children sleep with a light on), please consider sharing this
information with them.
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