More recently,
studies have increasingly pointed to the effect of exposure to different
types of light on melatonin production, which is a key factor in
determining not only how soundly we are able to sleep, but how “awake”
we are at peak times of the day and in the long run, whether our health
improves or deteriorates.
Melatonin, which is
produced by the pineal gland, located near the center of the brain, is a
highly light-sensitive hormone, which is to say that it can be “turned
on or off” to a large degree by the presence or absence of light. In
general terms, darkness or dim light stimulates melatonin production and
its resultant drowsiness, which enables us to sleep, whereas bright
light - whether it is sunlight or artificial light - stems the flow of
this sleep-inducing substance, making us more alert. While our natural
circadian rhythms are set to trigger our melatonin mechanism at certain
preset times, you might say that light can be used to override it.
When it comes to
influencing melatonin production and our resultant alertness or
sleepiness, what researchers have been finding is that not all light is
created equal. Like a rainbow, light comes in different colors, which
are transmitted via the retina of the eye to a mechanism called the
suprachiasmatic nucleus in the hypothalamus area of the brain that’s
responsible for regulating our circadian rhythm.
And though it might
seem counter-intuitive, the color that keeps us awake is blue, while the
ones more conducive to sleep are at the red end of the spectrum. And
these days, the light to which we’re exposed at the time our biological
clocks should be getting ready to crank out melatonin tends to be bluer
than ever, due primarily to the many computer-related activities that we
tend to engage in just before bedtime, whether they involve work, fun
and games, or communication and social media, as well as the phasing out
of old-fashioned incandescent bulbs that had more of a reddish glow to
them.
As a Harvard Medical School newsletter noted last year:
"Blue wavelengths -
which are beneficial during daylight hours because they boost attention,
reaction times, and mood - seem to be the most disruptive at night. And
the proliferation of electronics with screens, as well as
energy-efficient lighting, is increasing our exposure to blue
wavelengths, especially after sundown."
Click on this link to read the whole article:http://www.huffingtonpost.com/dr-mark-hyman/light-sleep_b_4239765.html
To read the Harvard Medical School newsletter click on this link: http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
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