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Science

Study: Exposure To Morning Sunlight Helps Managing Weight 137

Posted by samzenpus
from the here-somes-the-sun-there-goes-the-pounds dept.
jones_supa (887896) writes "A new Northwestern Medicine study reports the timing, intensity and duration of your light exposure during the day is linked to your weight — the first time this has been shown. People who had most of their daily exposure to even moderately bright light in the morning had a significantly lower body mass index (BMI) than those who had most of their light exposure later in the day, the study found. It accounted for about 20 percent of a person's BMI and was independent of an individual's physical activity level, caloric intake, sleep timing, age or season. About 20 to 30 minutes of morning light is enough to affect BMI. The senior author Phyllis C. Zee rationalizes this by saying that light is the most potent agent to synchronize your internal body clock that regulates circadian rhythms, which in turn also regulate energy balance. The study was small and short. It included 54 participants (26 males, 28 females), an average age of 30. They wore a wrist actigraphy monitor that measured their light exposure and sleep parameters for seven days in normal-living conditions. Their caloric intake was determined from seven days of food logs. The study was published April 2 in the journal PLOS ONE. Giovanni Santostasi, a research fellow in neurology at Feinberg, is a co-lead author."
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Study: Exposure To Morning Sunlight Helps Managing Weight

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  • Vitamin D (Score:3, Interesting)

    by Anonymous Coward on Thursday April 03, 2014 @10:04PM (#46657189)

    Is this caused by Vitamin D perhaps? It would be interesting to compare to people on supplements.

    Here in Edmonton, Canada, my family Dr. was participating in a study where her patients were tested to Vitamin D. I ended up having to take 2000 IU a day. Not that I don't get outside; during about six months of the year you won't see any daylight from 5 pm to 9 am.

    • Re: (Score:2, Insightful)

      by mjwx (966435)

      Is this caused by Vitamin D perhaps? It would be interesting to compare to people on supplements.

      Here in Edmonton, Canada, my family Dr. was participating in a study where her patients were tested to Vitamin D. I ended up having to take 2000 IU a day. Not that I don't get outside; during about six months of the year you won't see any daylight from 5 pm to 9 am.

      I highly doubt it, even if it were because of Vitamin D, people on placebos, erm sorry, supplements wouldn't get the same effect.

      However I think the cause it more due to the notion that if people are outside... they're moving instead of sitting down so they're burning more calories.

      • by icebike (68054)

        There is no effect of Vitamin D, via supplement or via Direct Sunlight [soylentnews.org].
        Vitamin D3 seems to decrease mortality (of all causes) by 11%.

        But I agree that this present study seems to be confusing cause and effect. If you are outside early and running around in the sunshine chances are its not the light of morning that has the effect, its merely the fact that you are more active.

        • by darkonc (47285)
          Well, supposedly, the study took levels of exercise into account -- and driving to work in the morning would account for 30 minutes of sunlight exposure, without any real exercise.
          • Well, supposedly, the study took levels of exercise into account -- and driving to work in the morning would account for 30 minutes of sunlight exposure, without any real exercise.

            Are you sure? I was under the impression that car windows filtered out a lot of UV. For example, you won't get sunburn while sitting in a car with your windows rolled up.

            If it's UV that matters here, and not simply bright visible light, then being in a car wouldn't do it I suspect.

        • by pepty (1976012)
          from the summary:

          and was independent of an individual's physical activity level, caloric intake, sleep timing, age or season. About 20 to 30 minutes of morning light is enough to affect BMI.

          What it wasn't independent of: small sample size, short duration, self reported diet.

    • by erroneus (253617)

      In order to wake up to sun light, a variety of factors must coincide, but chief among them is sleeping a little later instead of waking up at 5am to get ready for work and sitting in traffic for a long time just so you can sit in an office with unhealthy lighting by sunrise.

  • by Todd Palin (1402501) on Thursday April 03, 2014 @10:07PM (#46657203)
    Could it be that the fat people are just lazy and get up later, and don't get outside early. Maybe fat causes people to get less light in the AM. See the problem with the headline?
    • by Travis Mansbridge (830557) on Thursday April 03, 2014 @10:09PM (#46657221)
      True, but the summary does say "..independent of an individual's physical activity level, caloric intake, sleep timing, age or season."

      In any case causation is not proven, and this is a pretty small sample anyway.
      • by JMJimmy (2036122)

        There's no current measurement of a person's metabolic rate. I sleep later, eat more, and am older than my partner but my metabolic rate is higher due to previous lifestyle so I have a lower BMI. Anecdotal but it shows the flaw in the study. To show something like this you'd have to look at a larger but focused sample over a very long time.

      • by nbauman (624611) on Friday April 04, 2014 @12:09AM (#46657909) Homepage Journal

        If they really wanted to find out whether sunlight affected weight, they would have done a randomized, controlled trial.

        They would have randomly assigned half the people to getting exposed to sunlight early, and the other half to getting exposed to sunlight late.

        Instead, they let the subjects go their merry way and simply measured their exposure to sunlight during the day.

        These kind of studies give spurious results. For example, suppose the ones who are exposed to sunlight in the morning are getting up early to start their day jogging.

        • by clovis (4684) on Friday April 04, 2014 @12:44AM (#46658071)

          If they really wanted to find out whether sunlight affected weight, they would have done a randomized, controlled trial.

          They would have randomly assigned half the people to getting exposed to sunlight early, and the other half to getting exposed to sunlight late.

          Instead, they let the subjects go their merry way and simply measured their exposure to sunlight during the day.

          These kind of studies give spurious results. For example, suppose the ones who are exposed to sunlight in the morning are getting up early to start their day jogging.

          Well, no.
          You don't begin a line of inquiry with a randomized, controlled trial. You begin with a study to see if there may be a correlation.
          Why? If there's no correlation in a study, then there's no reason to spend the (much greater) money on a randomized trial.
          If there does appear to be a correlation, you report it so that you (and others) may pursue the inquiry further.

          • Pfft... rational thought and reason. This is /., where everyone who mis-interprets a statistical axiom is smarter than people who do this for a living. How else can they be self-righteous?
          • You are wrong in this case. If they just wanted to determine the correlation, they shouldn't have put the following statement in their abstract:

            Exposure to moderate levels of light at biologically appropriate times can influence weight, independent of sleep timing and duration.

            That's way beyond saying 'there's a correlation'

            • by timeOday (582209)
              Yes, and it would be so trivial to conduct a controlled study for this that there is no reason to release it at this point, when it is merely a correlation that popped out of a relatively small amount of data.
          • That's a fine way of looking at things, but then the most dramatic results you should report are "It appears to be a correlation, but more study is needed." There had better be no attempt to claim a causal linkage.

          • by nbauman (624611)

            True, it's appropriate to start with a correlational study before you go on to a randomized, controlled trial.

            This would have been a good study -- if they didn't come to an unjustified conclusion.

            Exposure to moderate levels of light at biologically appropriate times can influence weight, independent of sleep timing and duration.

            We don't know that from this study, because they couldn't control for all the other factors that might have influenced weight.

        • The article says "independent of activity level, sleep, and eating habits", so even people who eat and sleep the same amount and went jogging later in the afternoon were heavier.

          But I think the study size is too small and the duration too short to mean anything.
          • by nbauman (624611)

            They try to correct for those factors but they can never be sure.

            Maybe the biggest epidemiological study is the Nurses' Health Study, which has several thousand participants and has been going on for more than one generation. They've been recording a huge number of personal activities and medical developments. Then they run it through computers to find associations. Then they try to correct for all the factors. Then they do a randomized controlled study to find out if the association was spurious or if it r

      • With 54 people I don't think I would believe them when they said they controlled for ANYTHING.

    • by bluefoxlucid (723572) on Thursday April 03, 2014 @10:13PM (#46657249) Journal
      You're not reading this right. The solution is to get up later, when the sun is up, so that you are immediately exposed to sunlight early in the day.
    • by TWX (665546)

      Could it be that the fat people are just lazy and get up later, and don't get outside early. Maybe fat causes people to get less light in the AM. See the problem with the headline?

      I find it more likely that these people work outside during that part of the day and probably for much of their day, and since most jobs that work outdoors are more labor-intensive than most jobs indoors, that physical activity from the time one starts one's day may have more of an effect.

      The only way that this can really be s

      • I find it more likely that these people work outside during that part of the day ...

        Perhaps. There could be any number of explanations. The important thing to note is that this is an observational study. They just collected data on people, they didn't randomly assign people to get up early. Morning people and night owls differ in many ways. Their conclusion that "morning light" is the reason seems pretty far fetched. It is far more likely that the cause is late night tv with a big bowl of potato chips.

    • -1, self-righteous jackass

      Could it be that people that squawk "correlation does not prove causation" without knowing what that means are just lazy and don't bother to find out what the study actually does and does not cover?

    • Maybe it is evening/night people having their natural sleep schedules disrupted in our industrialized society that contributes to a higher BMI.

      AFAIK, morning sun has essentially the same spectrum as evening sun (slightly red due to the longer path through the atmosphere than at noon), and the same angle of incidence, so morning sun should have no different intrinsic effect than evening sun, if the rest of the day is spent in artificial light.

      Sounds like a VERY poorly controlled experiment.

      • by ehynes (617617)

        AFAIK, morning sun has essentially the same spectrum as evening sun

        No it doesn't. The authors address the differences in the spectrum in the third paragraph of the Discussion section of the study.

    • by Macgrrl (762836)

      I'm fat and I get up at 6:00 and am generally at work before the sun comes up. It must be because I'm lazy, and not because I commute and work stupid hours.

      • by bhiestand (157373)

        I'm fat and I get up at 6:00 and am generally at work before the sun comes up. It must be because I'm lazy, and not because I commute and work stupid hours.

        Well, you are too lazy to change your sig :). It's not an XP world anymore! Hell, it's even been looking a bit like a Mac world for the last few years.

    • ...says the guy too lazy to read the summary.

    • The other problem is lack of correlation for this hypothesis. There are large numbers of people whose work shifts that have them awakening at night to work during the night. If this study's conclusion is correct then the vast majority of these people should have a very high BMI, and the effects of working such shifts would have been noticed decades ago.

      Then there are people at the high latitudes who have months of very reduced sunlight, and thus wake up in the dark for weeks on end. Again, do we see the s

    • by bulled (956533)
      Can we just make this the default first post for all stories here? It isn't all that clever, and I would hope that the readers here would be able to regurgitate this rule on queue.
  • by globaljustin (574257) <justinglobal@gmB ... minus physicist> on Thursday April 03, 2014 @10:13PM (#46657259) Homepage Journal

    as the summary points out, it was only for 7 days with 54 people who used wrist mounted light sensors & 'food logs' but it's definitely worth a look

    sunlight in the morning has all kinds of physiological benefits...IIRC recently it was linked to higher immune function

  • "[The study] included 54 participants (26 males, 28 females)". No conclusions should be drawn from a study this small. Interesting as it may be to speculate.
    • Re: (Score:2, Insightful)

      by rgbatduke (1231380)

      For seven days. Either dredging the data from something else or (worse) looking for the effect!. Which is claimed to be 20% of BMI. I can refute this trivially within my own household. This is arrant nonsense. For me dropping 20% of BMI means losing 40 pounds, and gee, I'll bet nobody in their study dropped 40 pounds in seven days. So precisely how could the establish the correlation? By enrolling a handful of thin early risers and fat late sleepers and watching them for seven days and concluding th

    • by mobby_6kl (668092)

      What are you basing your judgment on? Please show your work.

    • by u38cg (607297)
      Hi, care to present the calculations you did to establish statistical power? No? The please stop talking about statistics as if you understand the subject as opposed to parroting pop-stats bullshit.
  • ... Look at the overweight+ people in Hawaii. And we live in the sun virtually year round!
    • by ScentCone (795499)

      ... Look at the overweight+ people in Hawaii. And we live in the sun virtually year round!

      If we can take their small sample and methodology as meaningful, and presume that you mean that Hawaiians all get up early and go right into the sun... then the point is that whatever lifestyle things make a lot of Hawaiians fat would be even worse if they all rolled out of the cot in their mom's basement and stayed there until lunchtime.

      • by laitcg (729768)
        Actually, TMK, most of us get up around sunrise and go outdoors. Maybe to spend the day at the beach (if they are not working). For sure the children do and to look at most of them.... something else is going on. Diet? I really think the small sample of the test was not enough to make judgment or rather a scientific proof/theory be valid.
  • Seems like the sample size is too small. Or the wrong sample. I'd like to hear more, but there is not much here.
  • Early to bed and early to rise, makes a man healthy, wealthy, and wise.
  • by BradMajors (995624) on Thursday April 03, 2014 @10:51PM (#46657493)

    Depression is correlated with sunlight exposure. Depression is correlated with weight gain.

    • by xelah (176252)
      Poor sleep, too, IIRC. This is why I'm sitting in front of a 125W compact fluorescent bulb right now. The sort of thing people use for growing, err, orchids. Not sure that'd work if I didn't work from home...but maybe if I didn't work from home I'd be outside long enough each morning not to need it.
  • "Early to bed and early to rise make a man healthy, wealthy and wise".

    http://books.google.com/books?... [google.com]

  • Yes I do get to see the sun rise at this time of the year, as I walk home from work.
    (I work Nights you insensitive clods)

  • That is, "We did a tiny study for a ridiculously short amount of time without anything like controls or double blindedness and found that exposure to morning light accounts for reductions of 20% of BMI at a statistically significant level.

    This could be true only if the lights one turned on when getting up "early" were frickin' laser beams attached to sharks that lopped of a major limb and ate it.

    April Fool's day was Tuesday. Why post this now?

    rgb

  • by Chas (5144) on Thursday April 03, 2014 @11:24PM (#46657683) Homepage Journal

    Eww. I don't like that stuff! I have blackout curtains on my bedroom windows to keep it from finding me.

    *Looks down at ginormo-gut*

    Hmm.

    NAH! I like sleeping late!

  • From the Federal Bureau of Get Your Ass Out Of Bed and Into Some Running Shoes. Snark aside, I prefer to get to work early, be home by 4, and do my 45 minute bike ride then. Although I did enjoy the few years I could bike to work.
  • by pspahn (1175617) on Friday April 04, 2014 @12:04AM (#46657883)

    Is exposure just a general "bathing" in sunlight? Is exposure light entering one's eyes and providing stimulation?

    Does this have anything to do with the fact that I have always had a very high metabolism yet my sleep patterns rarely follow a daily/hourly routine. I do not wake/go to bed at the same time every day. I am generally awake for 18 hours, then sleep for 8, so I sort of have a 26 hour day, which, of course, causes a number of other problems, but hey, it is what it is.

  • I guess this is why all the people living in Nordic Countries are obese.
    • Right? Its like these people didnt take 5 minutes to actually look at daylight lengths in places. Mexico comes to mind as well.
  • by David_Hart (1184661) on Friday April 04, 2014 @01:13AM (#46658177)

    First they tell us that dark chocolate is good for us because of the antioxidants and that it reduces the amount of fat that your body adsorbs from other foods.
    http://www.scientificamerican.... [scientificamerican.com]
    http://www.medicalnewstoday.co... [medicalnewstoday.com]

    Then they tell us that whole milk, cheese, etc. keeps us leaner
    http://www.npr.org/blogs/thesa... [npr.org]

    Now bathing in sunlight (don't forget the sunscreen) will help us manage our weight.

    So, I guess this means that eating dark chocolate, chasing it down with whole milk, while sitting in the sun and reading (good thing I own a Kindle) will help me get rid of those unwanted pounds... Ahhh... This IS the life.... (grin)

  • In northern countries a day in the winter is short, in southern countries it is longer. As we do not notice big difference between body weight in north and south, what is morning exactly? Is it the time just after you wake up and turn on light? Or is it time when the Sun rises? Or what?

  • A few years ago I started using a couple plug strips each with 6 'daylight' florescent bulbs during the winter (in Seattle).

    Gazing into them for the 10-20 minutes of groggy 'just woke up' time gives me, personally, a boost through the whole day; followed by being able to fall asleep at a reasonable hour in the evening.

    ymmv, but if you suffer from chronic sleep schedule drift, I would recommend trying it. You don't need an expensive 'lamp system' Just be sure to get the blue-ish 'daylight' bulbs, not the red

    • by SeaFox (739806)

      A few years ago I started using a couple plug strips each with 6 'daylight' florescent bulbs during the winter (in Seattle).

      "Daylight" florescent bulbs are just regular fluorescent bulbs with a color temperature of a bluer tone than normal. The actual light spectrum they put out isn't going to be vastly different. It's not the same as those sunlight-mimicking bulbs you're referring to.

      Have you tried this same routine with normal color florescent lights by the same manufacturer to see what happens?

      • by Kaenneth (82978)

        Just my personal experience, in any case, I wanted to simulate natural daylight as best as possible, since studies have shown that blue light is what triggers the circadian rhythm; it's also vital to not use the lights from early evening to bedtime if you try this.

        I guess I forgot to mention the cheap bulb holders (like this one http://www.hardwarestore.com/p... [hardwarestore.com] )

        I also wrote a program to adjust my video cards 'color temperature' setting depending on the time of day (but it only worked on XP)

        • by SeaFox (739806)

          I also wrote a program to adjust my video cards 'color temperature' setting depending on the time of day (but it only worked on XP)

          Perhaps you'd like to investigate this [justgetflux.com] then.

    • And on a related note, this "study" says that 500 lux is the magic threshold, and goes on to suggest that this level of light is difficult to achieve indoors. From personal experience, this is not true.

      I spent several years working in Commercial Real Estate Management, and one thing that was always a struggle was that we'd have folks in various office type environments arguing over whether or not it was too bright or not bright enough in the office (this was in addition to everyone fighting over wh
  • by Anonymous Coward

    The reason this happens is because there is a bundle of neurons in the hypothalamus called the suprachiasmatic nucleus. These neurons receive blue light from your eyes to precisely control sleep/wake rhythms. These neurons feed directly into the arcuate nucleus, the part of the hypothalamus that senses hormones and regulates your metabolism, hunger, and alertness.

    Source: Im a neuro-endocrinology researcher. Im also working on an open source genomics experiment to study this stuff. Join if you have genome an

  • Perhaps an as yet unknown agent contributes to obesity and makes it less likely for its sufferers to be up early enough to get some early morning sunshine. The lack of exposure at that time of day doesn't necessarily cause the obesity; nor does obesity directly prevent exposure to early bright light. They both could well spring from some other mechanism.
  • Obviously, I am once again an exception. I take the bike to work and I do it most of the week during spring, summer and fall. I have 30+ minutes of exposure to light in the morning. I'm still a fat fuck. That despite balanced meals, carbohydrate consciousness and aforementioned 3 to six hours of physical exercise per week.

    So frankly, fuck all those weight 'scientists'.

    • by Ceryx (1416491)
      Are you eating these balanced, low-carb meals at a calorie deficit in correlation to your daily exercise? If so and you aren't losing weight it might be time to check your thyroid hormone levels. Sunlight sure as hell didn't help me lose 25kg, but recording caloric intake while stopping sugar and simple carbohydrate consumption did.
      • by Kokuyo (549451)

        I have lost 23 kilos. I know how it works. But at the time, I've had no job. I was sleeping whenever and as long as I wanted, on most days I didn't have to be anywhere.

        Then I found another job. 10kg returned in no time.

        I'm telling you, what makes me fat is job induced stress and there is just no way getting around that, unless I want to get out of IT (which, in turn, would bring a lot of anxiety with it).

  • This comment is just as redundant as the request to the editors to throw garbage like this into the waste-bin instead of treading us to it and waste even more bits.

    Correlation is no causation and here Northwestern Medicine ought to pay back the funding and instead be supplied with brown bags for over their heads: "This bag covers gently the red face of someone who bungled it on science"

    Yep, this case could make it into a new standard textbook example why correlation is obviously no causation. It is so blood

  • Seriously? How is that even statistically significant?
  • The study was small and short.

    Never mind.

  • by ndykman (659315) on Friday April 04, 2014 @01:22PM (#46662483)

    For all those yelling "This is clearly bad science", it's not. The summary is not the paper. The paper notes that there is a correlation between a certain pattern of light exposure and BMI in their sample group. The hard part about the paper is the models they used to capture temporal patterns of light exposure and determining if they are valid. The paper does discuss the model in detail and notes that there are issues that it fails to address.

    The rest of the analysis is fairly accepted sensitivity analysis, which factors in the sample size. Also, the paper notes that there have been other studies in animals that have linked light exposure to changes in metabolism, so there is a potential for the mechanism to be causative. But the paper clearly notes in the summary that directionality of the found relationship can't be determined from this study. In other words, the paper just suggests more avenues of research into the links between light exposure, sleep rhythms and metabolism and suggests that the temporal aspects of exposure could play a role.

    Finally, the intervention that it suggests is fairly harmless. If people start getting more sun in the morning, that's probably okay overall.

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