Light Exposure And Its Affects On Sleep

[davekm]

I have read that exposure to blue light two hours before sleep, reduces melatonin.

 

Which of the following scenarios would produce the least blue light exposure?

 

Bed lamp + book

Backlit e-book reader

Clip on reading light.Like this one

[davekm]

This should probably have went in physics

[CraigD]

I have read that exposure to blue light two hours before sleep, reduces melatonin.

Me, too, though not that it need be some specific time before sleep. The literature I’ve read suggests it may be most effective around the time of waking, as “dawn simulation”.

 

The link between various neuropsychological disorders, such as SAD and blue light, has been well known since the 1990s, and forms the basis for therapies from simply getting outside more to staring at special lamps. However, how effective this is questionable and controversial – this Wikipedia article section has a summary and some links.

 

Which of the following scenarios would produce the least blue light exposure?

 

Bed lamp + book

Backlit e-book reader

Clip on reading light.Like this one

The shape of the appliance is less important than its light-producing elements, I’d guess. You’d have to look at their spectra, or find a reference that has for a particular device, to know definitively.

 

However, if a light source appears white (or, of course, blue), it must have a fair amount of blue in it. The light with the least blue, then would be one that appears red.

 

Given the questionable efficacy of even strong light therapy devices purpose-built for this, I’m inclined to conclude that selecting a lamp for its effect on melatonin isn’t very worthwhile.

[davekm]

I'm not looking to increase melatonin. Just stop blue light from decreasing it. In that sense, I think it's a good idea to decrease late night blue light exposure.

 

Whats spectra? Is that the wattage?

[CraigD]

Whats spectra?

Spectra is the plural of spectrum. In optics, a spectrum is the “spread”, or distribution, of the frequency (which can also be expressed as the wavelength) of individual photons in a specific light, and is essentially synonymous with a numeric or graphic representation of this.

 

The key concept here is that most natural and artificial light sources produce light with broad, “smeared out” spectra. A related concept is that the “white” light has no characteristic photon frequency – it must consist of photons of different frequencies (due to a quirk of how our eyes are built, at least 3 – if our eyes were built differently, fewer or more frequencies would be required)

 

Here are examples of spectra, all of what an ordinary person would call “white light”

 

For example, this graph (from wikipedia)

shows 2 spectra: the yellow, that of sunlight outside of Earth’s atmosphere, the red, inside it, at sea level.

 

This one (from wikipedia)

shows the spectrum of a typical florescent lamp.

 

This one

shows the spectrum of light from an incandescent flashlight bulb. See it’s source webpage, LEDMuseum.org’s SPECTRA OF INCANDESCENT FLASHLIGHTS for many others, showing the subtle differences between the light produces by even very similar incandescent lamps.

 

Notice that the scale of the sunlight spectra are much wider than the 2 artificial lamp spectra, so to compare them, ignore the parts outside of the "visible" band marked on the solar spectra graphs.

 

Light that an ordinary person would call “white” must have its spectrum average (in a somewhat complicated way) to about equal amounts of light at 445, 535, and 575 nm.

 

Light that an ordinary person would call “blue” will have most of its spectrum concentrated around a wavelength of 445 nm.

 

Is that [spectra] the wattage?

No. Wattage is power – the rate at which work is done – expressed in units of watts.

 

When comparing lamps of similar design (eg: incandescents to incandescents) power is a useful relative measure of their luminosity, or intensity.

 

As a general rule, increasing an incandescent lamp’s power shifts its spectrum “blueward” (to the left in the above diagrams) to shorter wavelengths, decreasing it shifts it "redward". This is why incadescent bulbs at very low power look dull red. Florescent lamps’ spectra tend to remain more constant with changes in power, but also are as a rule can’t have their luminosity varied as easily via changes in power. This is why most of them are not recommended for use in “dimmable” lamp fixtures.

[Guest MacPhee]

I'm not looking to increase melatonin. Just stop blue light from decreasing it. In that sense, I think it's a good idea to decrease late night blue light exposure.

 

Whats spectra? Is that the wattage?

 

I think you're right about blue-light exposure. We humans don't naturally experience much blue light. So it's bound to be upsetting to us.

 

The light that we naturally experience, is the yellowish light from the Sun. This light has, in recent times, been well reproduced by our familiar incandescent light-bulbs. These provide a warm and pleasant light. Attuned to our natural instincts, which respond calmly to a smooth output of light, concentrated in the yellow region of the spectrum.

 

To demonstrate this, study CraigD's graphs, which he's kindly provided in his post#5. You'll see the smoothly-curving spectral signature in the 1st graph (Solar Radiation Spectrum). And in the 3rd graph (Incandescent Bulb). Both nice and smooth.

 

Now - by contrast - look at the 2nd graph (Fluorescent Lamp). What do you see - hideous jagged spectral spikes! Quite unnatural, and hardly likely to induce sound sleep, don't you think?

[davekm]

What about new led bulbs? What is their spectra? I can't find anything on this.

Edited June 11, 2012 by davekm

[davekm]

bump

[davekm]

 

Given the questionable efficacy of even strong light therapy devices purpose-built for this, I’m inclined to conclude that selecting a lamp for its effect on melatonin isn’t very worthwhile.

 

It's not the effect on melatonin i'm looking for, it's the lack of effect. Burgeoning evidence suggests blue light decreases melatonin. So I wonder if I should avoid all blue light in the evening.

 

Is color temperature relevant in a bulb, or do i look for spectrum only?

 

Is white light the same as daylight or is that red light?

Edited August 14, 2012 by davekm

[labelwench]

This is an interesting thread to me as I work graveyard shift three nights of the week and have to be very cognizant of my exposure to light and activity because of the effect on my sleep.I find that the 'dead of night' or the hours between 3:00-5:00 a.m. are the hardest to stay alert through, especially if I have not had much sleep prior to shift.

 

As day begins to break, I can almost feel my circadian rhythms resetting and my body energizing no matter how little sleep I had the night prior. As winter approaches, the energizing period moves forward to 6:00 a.m. and then 7:00 a.m. and seems to shift with the seasons.

 

I have been working graveyards for seven years and observing it's effects on others and myself, a bit of a subjective field experiment. It has been and remains quite an interesting exercise. My bedroom window is completely blacked out to remove the influence of light while I am resting.

[Pincho Paxton]

Well, if you want the opposite to a Blue Light effect then stare at a red light. In my theory, blue light is created by a positive flow, and red light is created by a negative flow. So basically, the opposite effects should result from a Red light. You could buy a torch like this...

 

http://www.amazon.co.uk/Gerber-Recon-Task-Light-Torch/dp/B0006TU75I/ref=sr_1_1?ie=UTF8&qid=1344964455&sr=8-1

 

I used to stare at these torches in bed under the sheets as a child. Then I would close my eyes, and try to recreate the colours in my imagination. I could do it, and change the colour in my imagination to any other colour. It was very therapeutic.

 

I think that it has some benefits.

[davekm]

It's not the effect on melatonin i'm looking for, it's the lack of effect. Burgeoning evidence suggests blue light decreases melatonin. So I wonder if I should avoid all blue light in the evening.

 

Is color temperature relevant in a bulb, or do i look for spectrum only?

 

Is white light the same as daylight or is that red light?

 

thanks for the replies. Just bumping this so the questions can be answered by somebody

[sman]

This is an interesting thread to me as I work graveyard shift three nights of the week and have to be very cognizant of my exposure to light and activity because of the effect on my sleep.I find that the 'dead of night' or the hours between 3:00-5:00 a.m. are the hardest to stay alert through, especially if I have not had much sleep prior to shift.

 

As day begins to break, I can almost feel my circadian rhythms resetting and my body energizing no matter how little sleep I had the night prior. As winter approaches, the energizing period moves forward to 6:00 a.m. and then 7:00 a.m. and seems to shift with the seasons.

 

I have been working graveyards for seven years and observing it's effects on others and myself, a bit of a subjective field experiment. It has been and remains quite an interesting exercise. My bedroom window is completely blacked out to remove the influence of light while I am resting.

 

What’s your latitude, Rose? The Yukon covers quite a range of ‘em.

 

I grew up in Alaska at about latitude 49. At that northness day/night cycles can get disorienting. More for others than for me, really. There is about a month in the year when the sun never comes up at all, although it illuminates the horizon at mid-day. Of course I always was surrounded by Alaskan mountains… In the summer, of course, the sun simply goes round in a circle in the sky for a couple of weeks.

 

I’ve worked graveyards off-and-on in Alaska as well as in other parts of the country and I too have noticed the drag between 3 & 5am and the shot of energy about 6am. I also suffer from episodic cluster headaches that, in hindsight, may be correlated with these disruptions in my sleep cycle. I’d be willing to experiment with blue-light therapies. I, like all sufferers of the condition, would be willing to try most anything if I thought it might help even a little. Suffice to say, I am very personally interested in the effects of lighting on the sleep cycle and follow any links on the subject.

[labelwench]

Originally posted by sman:

 

What’s your latitude, Rose? The Yukon covers quite a range of ‘em.

 

Latitude : 60.7129 Longitude : -135.07

 

Whitehorse, Yukon is also known as 'the land of the midnight sun' and we experience the extended daylight hours of summer and short daylight hours during December and January.

[labelwench]

I have read that exposure to blue light two hours before sleep, reduces melatonin.

 

Which of the following scenarios would produce the least blue light exposure?

 

Bed lamp + book

Backlit e-book reader

Clip on reading light.Like this one

 

Based on the information at the following article, from which this paragraph is taken, I would suggest a bed lamp with an incandescent 'warm white' bulb and a warm gold/orange shade and book. Depending on your e-book reader, the backlight may be dimmed but I do not know if you can affect the color of the back light. I have one of the clip on reading lights you show and mine has a blue/white LED, which is the spectrum I believe you are trying to avoid.

 

One way to fool the body into producing melatonin earlier so you can go to sleep earlier is to select warm-color light bulbs and have them dimmed in the evening. Another way is to wear DARK AMBER or ORANGE sunglasses in the evening to block blue light (short light wavelengths). And of course, that’s why sleep experts advise against using a computer or watching TV shortly before bed.

 

http://www.mhealthta...onin-and-sleep/

 

Reading before bed affects people differently, depending on the topic. Some books are very relaxing whist others are very engaging and 'hard to put down'. Regardless of what light you are using, a book that is too stimulating may prove counter-productive.

 

Here is a simple color temperature chart with photographs that clearly show the difference. http://www.soslightbulbs.com/colortemperaturechart.aspx

Edited August 15, 2012 by Under the Rose

[davekm]

Incandescent bulbs have been phased out in my country (UK) and many others. Is the color of the lamp shade important then?

Edited August 15, 2012 by davekm

[davekm]

It's not the effect on melatonin i'm looking for, it's the lack of effect. Burgeoning evidence suggests blue light decreases melatonin. So I wonder if I should avoid all blue light in the evening.

 

Is color temperature relevant in a bulb, or do i look for spectrum only?

Found out that color temperature is a measure of spectrum. So it is very relevant.

 

Is white light the same as daylight or is that red light?

No, white light is in between red and blue

Edited August 15, 2012 by davekm