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Posted at 10:30 AM ET, 08/ 5/2009

Sleeping Through Sunlight: Not a Success

By Ann Posegate

Wx and the City

* Real Heat? Full Forecast | NatCast | Rethinking Hurricane Forecast *

Photo courtesy UCAR

"This is getting ridiculous," I think, cursing the solstice as I awake around 5:30 a.m. when the first hues of orange and pink sunlight strike my bedroom walls on a late-June morning.

It's not that I don't appreciate the sun and all the benefits it brings, including fueling Earth's weather. But, despite putting up mini-blinds and dark curtains on my east-facing bedroom windows and covering my head with a pillow, the first persistent sun ray of the day -- all 120 watts per square meter of it -- seems to burst its way through a glitch in the system, straight to my eyes. I sigh as I roll over and shut off the alarm clock hours before it is supposed to sound ... there's no point in attempting to fall back asleep now.

Formerly a chronic night-owl, I've been defending myself against the sunrise since last year, when I moved into a place with more sunlight. (Before that, I had inhabited a light-deficient abode.) Since then, my houseplants and I have enjoyed a bright apartment, but my sleep-wake cycle has been off. I'm guessing I'm not the first person to have her sleep affected by the amount of sunlight she receives.

Come to find out, sunlight has a lot to do with regulating the human body, including stopping production of the hormone melatonin that induces sleep.

Keep reading for more on sunshine and the sleep-wake cycle...

As you've probably noticed, humans are diurnal animals: we sleep during the night and are active during the day, as opposed to nocturnal creatures that are active at night (e.g., an opossum) or crepuscular creatures that are active at dawn or dusk (e.g., a firefly). Without exposure to sunlight, our bodies would operate on a 25-hour daily cycle. However, add sunlight to the picture, and it becomes a 24-hour cycle: a day and night on Earth.

When sunlight enters our eyes, it triggers photoreceptors (light-detecting cells) in the retina. These alert the body's "biological clock" (a small area in the brain), which sends signals to other areas of the brain, telling the body it's time to wake up: production of melatonin is halted by the pineal gland; body temperature rises; urine production and blood pressure increase; etc.

Lifestyle can affect how much sunlight and darkness we're exposed to, and thus affect our sleep. People who travel across time zones often experience jet lag symptoms, including disruptions to their normal sleep-wake cycle. Their bodies can adjust to a new schedule of sunlight, though it may take a few days. Those who work night shifts can have a more difficult time adjusting, since they are not exposed to enough sunlight and do not sleep during the night, when their melatonin production is highest (check out this diagram). Even those of us who work in office buildings can experience effects on our sleep-wake cycles from lack of sunlight during the day.

Weather and climate can affect the sleep-wake cycle, too. For example, sufferers of Seasonal Affective Disorder, a disease that can affect people who live in northern latitudes with long, dark winters, sometimes have to go through phototherapy (exposure to powerful artificial light) to reduce their symptoms.

For people who have trouble falling asleep, a helpful and surprising tip is to get outdoors for a half-hour to hour of early-morning sunlight (before 8:30 a.m.) each day. This helps the body's clock get back on schedule. For people who wake up too early, increasing your exposure to evening sunlight may help.

I've experienced a long and sometimes challenging adjustment this past year. The good news is that, given a chance, the human body can adapt to a more biologically appropriate sleeping schedule, and I've learned to listen to it. After years of resisting the thousands of years of evolution that have perfected the human biological clock, who would have thought that I'd start waking up with the sun?

Have you experienced a shift in your sleeping patterns based on sunshine or other types of weather? Let us know in the comments section below.

Current sunrise and sunset times for Washington, D.C.
Sleep and Circadian Rhythms
Brain Basics: Understanding Sleep
Jet Lag and Shift Work
Lifestyle Practices that Can Improve Sleep
How to Fall Asleep
Diurnal and age variations in human melatonin levels (from this study)

By Ann Posegate  | August 5, 2009; 10:30 AM ET
Categories:  Health, Posegate, Wx and the City  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Typical Summer Stuff, Then Real Heat?
Next: PM Update: Quiet Gives Way to Tricky


The headline is "The Capital Weather Gang", not "The Capital Insomniac Gang." Who cares about your body's urine production? This is an article only your mother and your therapist can love. Nothing personal.

Posted by: Tess6 | August 5, 2009 11:29 AM | Report abuse

Ann, welcome to the club! I am also super-sensitive to light in the morning. So much so that I, too, often wake up with the pillow covering my head. (My wife finds this quite amusing!) I actually look forward to overcast mornings.

On a related note, I stuck it out all of 7 months at an overnight job just out of grad school. I think some people are more cut out for that than others. But I am definitely not one of them. The lack of sun during the day, while I tried my best to sleep during 9-to-5 "working" hours, took its toll.

Posted by: Dan-CapitalWeatherGang | August 5, 2009 12:27 PM | Report abuse

I thought this was an interesting article! Keep it up and dont listen to the negative comments!

Posted by: where_is_snowmonster | August 5, 2009 12:30 PM | Report abuse

Summer doldrums seem to be getting to folks lately. We need a good hurricane to track or something.

Posted by: Ian-CapitalWeatherGang | August 5, 2009 1:26 PM | Report abuse

Now that the sun is rising after 6 AM, responding to the 5:30 alarm can be a hassle.

The intermittently gloomy rainy spells we've had this year are tending to prolong SAD-type symptoms. I don't experience that much depression during the winter due to the combination of the holidays, followed by snow-anticipation fever. Last winter was really bad, though. There was no snow to begin with, except for meaningless flurries. [Normally the early appearance of flurries tends to presage a "train" of accumulating snows as the winter progresses; this didn't happen last winter.] When the lone big snow hit, it was already meteorological spring; then the 'much-needed rain' crowd continued to bedevil me well into June with their series of "training" deluges, extending my SAD-style symptoms. The best weather thus far this year has been the Northwoods-style "summer" we had up until around ten days ago.

Posted by: Bombo47jea | August 5, 2009 1:36 PM | Report abuse

Tess6, what a nasty comment. When the weather gets "boring" there is not much else to do. and 90's and sunshine are boring! So this article is change of pace.

Posted by: RWJ1990 | August 5, 2009 2:35 PM | Report abuse

Being a sufferer of SAD and I've often compared myself to a hibernating bear. I want to crawl into a cave about Thanksgiving time (after a big meal) and wake up about mid-April. Cold days, snow storms and long dark nights are only good for sleeping. However, if sunshine interferes with your sleep patterns during spring and summer, just get a black sleep mask. I've taken many mid-afternoon naps with those. My bedroom has a skylight so curtains don't help much.

Posted by: Baltimore11 | August 5, 2009 2:39 PM | Report abuse

Great article Ann.

A reformed night owl myself, I always look forward to the time change in early November -- makes waking up a lot easier for me.

Posted by: JamieYPotomac | August 5, 2009 3:17 PM | Report abuse

The relationship of sunlight to staying awake that you mentioned overlooks one very important thing, however. Many people have a natural tendency to feel drowsy (and, if possible, to sleep) for a few hours each day in the early-to-mid afternoon. This typically occurs during the hours of most intense sunlight and warmest temperatures, so the presense of sunlight does NOT necessarily prevent someone from sleeping. In tropical countries, this early-afternoon nap is called a siesta, and is a long tradition. Buisnesses even shut down during the afternoon to allow employees to take the nap, and then back open up again in the late afternoon, and stay open well into the night to compensate. I find, myself, even here in the D.C. area, a strong tendency to get drowzy after lunch (and I'm glad I'm retired, so time now allows it).

Posted by: MMCarhelp | August 5, 2009 5:55 PM | Report abuse

Thanks for all the comments.

@Bombo - I agree about the best weather so far this year.

@Baltimore11 - Thanks for the advice.

@MMCarhelp - I call that the "post-lunch food coma." In all seriousness though, I think the custom of an afternoon siesta is a great idea. I'm sure the warm summer temperatures and energy needed for digestion have something to do with early afternoon sleepiness. I haven't come across any information linking it directly to sunshine, though that would be interesting to find out.

Posted by: Ann-CapitalWeatherGang | August 5, 2009 6:22 PM | Report abuse

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