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Exposure
to Bright Light Can Improve Sleep
If you suffer from early morning awakenings insomnia or even
sleep onset insomnia, then you may not be getting enough bright
light.
Bright light is often characterized as having at least 5,000
luxes. (A lux is equal to the light from one candle.) Most
lights that are in offices and homes where you likely spend
the vast majority of our time generally have about 500 luxes,
no where near 5,000.
This low exposure to light can alter melatonin secretion and
the body-temperature rhythm resulting in sleep difficulties.
Early morning awakening insomnia
People with early-morning awakening insomnia have the problem
of waking up too early in the morning and being unable to
go back to sleep. This problem tends to increase with age
and is associated with a decreased total sleep time and excessive
daytime sleepiness.
Individuals who experience morning awakenings often have a
body temperature rhythm that rises too early in the morning.
Studies show that increased exposure to evening bright light
can decrease early morning awakenings by delaying the body
temperature rhythm so that it will not rise too soon.
For example, according to one study: Following only two nights
of bright light therapy exposure, individuals with early-morning
awakening insomnia experienced much improved sleep and daytime
functioning that lasted for up to a month after therapy.
The study results show that four hours of bright light therapy
for two consecutive nights produced a two-hour delay of the
circadian phases of body temperature and melatonin rhythm
in otherwise healthy people with early morning awakening insomnia.
Over a one month follow-up period, these people showed a greater
reduction of time awake after falling asleep, a trend toward
waking up later in the morning, and a greater total sleep
time, as compared with a control group.
Sleep Onset Insomnia
Sleep onset insomnia is characterized by a body-temperature
rhythm that falls too late at night. This often results in
an inability to fall asleep within a reasonable amount of
time after going to bed. Because sunlight causes body temperature
to rise, sleep onset insomniacs can cause their body temperature
to rise earlier and fall earlier, and therefore fall asleep
more easily, by increased exposure to early morning sunlight.
In other words, a sleep onset insomniac should open the drapes
early in the morning, take a walk outside and any other activity
that will increase their exposure to morning bright light.
Bright Light and Mood
In addition, not enough exposure to bright light can also
harm daytime mood, energy, and alertness. For example, it's
well known that people's mood and energy are worse during
winter months than summer months because the days are shorter
during the winter and consequently offer less sunlight. Likewise,
people who live in northern latitudes, where sunlight in the
winter months is less, are more likely to experience seasonal
affective disorder, which is characterized by depression and
sleep difficulty in winter months.
Light Boxes
Another way to increasing exposure to bright light is to use
artificial bright-light boxes. They contain special bulbs
that emit 5,000-10,000 luxes of light, which is about equal
to a sunrise or sunset. They should be used for about 30 minutes
to increase early to late exposure to bright light. This can
be done, for example, while one is reading, watching television
or working on the computer.
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