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Study: Exposure To Morning Sunlight Helps Managing Weight
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."
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.
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?
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
Thank you Dave Raggett
"[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.
... Look at the overweight+ people in Hawaii. And we live in the sun virtually year round!
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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.
Depression is correlated with sunlight exposure. Depression is correlated with weight gain.
Early to bed and early to rise, makes a man healthy, wealthy, and wise.
I don't know about healthy. But late to bed, late to rise, seems to make you more intelligent and wealthier That study looked at 1000 people, rather than 54. If both studies are accurate, it looks like you can be smart, fat, and rich, or healthy, poor and stupid.
Early to rise and early to bed makes a man healthy, wealthy, and dead.
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!
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THANK GOD!!!
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 same correlation there? This type of thing should be easy to study in places like the Amundsen–Scott South Pole Station, where those that stay over winter experience little sunlight for a few months non-stop.
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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.
Someone flopped a steamer in the gene pool.
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The second mouse gets the cheese.
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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....
http://www.medicalnewstoday.co...
Then they tell us that whole milk, cheese, etc. keeps us leaner
http://www.npr.org/blogs/thesa...
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)
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.
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 whether or not it was too hot or too cold....another conversation entirely). Anyway, as a solution, I had my team buy light meters, and we used the OSHA thresholds for safety for egress lighting as well as the lighting designer's standards from the blueprints of the facility as a guideline, and I would instruct my team to ensure that the light levels were at LEAST 35 footcandles, and at MOST 90 footcandles (in most cases).
500 lux = 46.45 footcandles. I can tell you that the vast majority of the workspaces in conventional offices (from my experience) is usually in the 50 to 60 footcandle range. The point being, I disagree with the study claiming that it is difficult to achieve indoors, or that you specifically need to do something extraordinary to achieve this light level.
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.