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Do you think the amount of light at night affects your weight?

Answered on August 19, 2014
Created October 12, 2010 at 7:50 PM

I just found this link

http://ca.news.yahoo.com/s/afp/101011/health/health_science_obesity_sleep

and it implies that even some light at night can affect weight gain. I myself instictively want total darkness when I sleep and wear a mask to make sure I get it.

Any thoughts?

04293f705870e1837b8670d3c1cd5f67

(2261)

on October 14, 2010
at 10:57 PM

Yes, I just finished that book and highly recommend it.

77877f762c40637911396daa19b53094

(78467)

on October 12, 2010
at 11:54 PM

5. is too funny- never would have thought of that!

F419c479f4a3db6b0f3c85a02da0c348

(0)

on October 12, 2010
at 09:54 PM

"it seems that the presence of the moon doesn't fit well in the picture of being in the dark when sleeping." from someone who has slept their share outside - the moon and stars have nothing on streelights and other ambient, artificial light. Most people I know sleep much better in the field even when conditions are lousy.

1dd5986edc44148c39247cfa61fbe881

(300)

on October 12, 2010
at 08:09 PM

I would argue that man has an instinctual craving for shelter, and sleeping out under the stars isn't necessarily a safe solution, evolutionarily speaking. Thus, shelters are built, caves are found, etc. A nap, too, isn't typically a full circadian sleep cycle (unless you are REALLY lucky) -- there are some excellent studies out there detailing nap length and brain chemical impacts. From what I've read, naps don't equal a good night's sleep.

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4 Answers

1
25ed4acfb632d928507f8673bcb0923a

(650)

on October 12, 2010
at 11:19 PM

The title of the original article is "Light at night increases body mass by shifting the time of food intake" (Fonken, et al., 2010).

http://www.pnas.org/content/early/2010/09/30/1008734107.abstract

Here a few points:

  1. The American Free Press says, "Sleeping with light on may lead to weight gain: study." Well, possibly...if you are a) a mouse, and b) you are not sleeping when the aforementioned light is on.

  2. The original study itself is interesting. There were three groups of mice: a group with the standard light/dark cycle, another group with a light/dim light cycle, and a group with continuous light.

  3. All mice had some "bright" light. They were housed for 16 hours in 150 lux (comparable to an overcast day). But the dim-light mice spent their other 8 hours in 5 lux (which would be equivalent to twighlight). The "dim light" in this study is still therefore still fairly bright. By the way, a full moon in the US would be about 0.3 lux.

  4. The dim-light group gained more body mass and more fat over time than the standard-light-cycle group. They also had more impaired glucose tolerance. Total food consumption was the same for all groups! The dim-light group ate more during "daylight" hours than the standard-light group, so essentially the timing of their normal eating behavior was off. When the dim-light mice were restricted to their normal eating times they did not gain weight.

  5. Mice are nocturnal. Whoops. The "dim-light" happens to be presented when they are most awake.

77877f762c40637911396daa19b53094

(78467)

on October 12, 2010
at 11:54 PM

5. is too funny- never would have thought of that!

1
9bc6f3df8db981f67ea1465411958c8d

on October 12, 2010
at 08:02 PM

I was wondering about the light thing. Robb Wolf is a die hard proponent of a pith black room, but on an evolution perspective, it seems that the presence of the moon doesn't fit well in the picture of being in the dark when sleeping.

Also, we often talk about our ancestors taking naps during the day. Are we also saying that those naps aren't quality sleep since the sun is shinning?

F419c479f4a3db6b0f3c85a02da0c348

(0)

on October 12, 2010
at 09:54 PM

"it seems that the presence of the moon doesn't fit well in the picture of being in the dark when sleeping." from someone who has slept their share outside - the moon and stars have nothing on streelights and other ambient, artificial light. Most people I know sleep much better in the field even when conditions are lousy.

1dd5986edc44148c39247cfa61fbe881

(300)

on October 12, 2010
at 08:09 PM

I would argue that man has an instinctual craving for shelter, and sleeping out under the stars isn't necessarily a safe solution, evolutionarily speaking. Thus, shelters are built, caves are found, etc. A nap, too, isn't typically a full circadian sleep cycle (unless you are REALLY lucky) -- there are some excellent studies out there detailing nap length and brain chemical impacts. From what I've read, naps don't equal a good night's sleep.

1
1dd5986edc44148c39247cfa61fbe881

(300)

on October 12, 2010
at 08:00 PM

The short answer is yes, absolutely yes. Levels of light can and do have a direct impact on your hormone release and control.

For an excellent discussion, please see "Lights Out: Sleep, Sugar, and Survival" by T.S. Wiley

04293f705870e1837b8670d3c1cd5f67

(2261)

on October 14, 2010
at 10:57 PM

Yes, I just finished that book and highly recommend it.

0
62ed65f3596aa2f62fa1d58a0c09f8c3

(20807)

on October 13, 2010
at 04:09 AM

Personally, I think it's more of a stress thing. If light disrupts sleeping patterns or leads to insomnia, then I think it will effect weight and health in general. But I would be a bit surprised if mild amounts of light at night effect all people negatively. IMO, humans are more flexible than that. In paleo times, they would not always have had shelters to sleep under and some primal shelters are not fully light proof. In this day and age with modern stresses and concerns, some individuals who are not good sleepers to start with may well benefit from every aid possible though, including enhancement and refinement of indicators of day and night like light levels. However, I have not yet seen good evidence that small amounts of light at night negatively effect all humans. There have been times at night, while sleeping in my tent in the dessert, when I woke up for a moment and thought that the sun was coming up due to the brightness in my tent, only to look at my watch and realize that no, it was only due to a very bright full moon that night! THe moon can also give out more overall illumination than my outdoor porch light.

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