Are energy efficient LEDs de-energising you?!

[Adsibob]

https://www.theguardian.com/environment/2022/sep/14/increase-in-led-lighting-risks-harming-human-and-animal-health
 

thoughts???

[SteamyTea]

Some screen use before bedtime might be OK for your sleep after all

The blue light that smartphone and laptop screens give off may not affect your sleep if you only get a small dose of it

 

HEALTH 5 September 2022

By Jason Arunn Murugesu

 

The blue light from screens can delay you nodding off if you get too much of it

Realstock/Shutterstock

 

A bit of screen time before bed might not actually damage the quality of your sleep too much.

Several studies have found that pre-sleep exposure to blue light, which is produced by laptop and smartphone screens, can make people less sleepy and affect the quality of their rest. One of the supposed mechanisms for this is that the blue light makes bodily systems block the hormone melatonin that usually makes you feel drowsy.

To dig a little deeper, Christine Blume at the University of Basel in Switzerland and her colleagues wanted to test whether blue light that affects only intrinsically photosensitive retinal ganglion cells (ipRGCs) in the eyes would have any effect on subsequent sleep quality.

 

How the immune system enables the body to heal itself Daniel Davis at New Scientist Live this October

These eye cells, alongside cones and rods, are activated by light, but ipRGCs are particularly sensitive to blue light and are thought to play a major role in setting the body’s internal circadian rhythms, says Blume.

The researchers tested 29 people in a sleep lab with exposure to two types of light. The participants, with an average age of 23, all had healthy sleep histories. On one of the nights they spent in the lab, the participants were exposed to one type of light from a screen for an hour, ending 50 minutes before they typically went to sleep. The participants’ average bedtime was 11pm. About a week later, the participants had a night when they were exposed to a different light condition.

The two different lights would have looked nearly identical to the participants. However, one was made up of a high proportion of blue light, which would be picked up by the specialised retinal ganglion cells, whereas the other had a far lower proportion of blue light and so wouldn’t be picked up by these cells. An electroencephalogram (EEG) machine was used to measure brain activity while the participants slumbered.

 

 

Read more: Tracking sleep disruptions could improve nerve pain treatments

 

To assess how melatonin levels changed, the researchers took saliva samples from the participants every 30 minutes in the 5 hours before the volunteers fell asleep and also took samples in the morning. The participants were questioned about how sleepy they felt before bedtime. In the morning, they were asked how well they slept and how alert they felt.

The blue light that was supposed to affect melatonin reduced levels of the hormone in the blood by about 14 per cent on average, compared with the other frequency of light, but no effect was found on self-reported sleep quality. “Melatonin and sleep are probably not as closely linked as people think,” says Blume.

She says there are several reasons why blue light may not have affected the participants’ sleep.

 

Read more: Getting a little more sunlight is a simple health win for everyone

 

The need to sleep at a certain time is largely based on two components: the pressure to go to sleep, which builds during the day, and the circadian clock, which is the body’s internal clock that regulates when we need to sleep and wake up on a 24-hour cycle. The interplay of these factors also has an effect.

In young people with no particular health problems, like those participating in the study, sleep pressure may simply overpower the effects of blue light on the circadian clock, says Blume.

The study also suggests that blue light’s effect on sleep quality may be driven by other eye cells rather than ipRGCs, she says. Blume adds that had they kept the screens turned on closer to bedtime, it may have taken longer for the participants to fall asleep, but the researchers wanted to question them and let them brush their teeth.

“This study shows that exposure to bright light in the evening for a limited amount of time does not necessarily impact sleep,” says Blume. “I don’t think this study changes our overall perspective on blue light’s impact on sleep, it just adds a piece of information to the existing evidence.”

“This does not show that blue light before bed will not affect sleep,” says Stuart Peirson at the University of Oxford. “It just shows that the type of blue light they used, at the intensity the used, did not in this study.”

“I think what this paper speaks to is how complex the processes of sleep and wakefulness can be,” says Hugh Selsick at University College London. “The role of melatonin in sleep-wake regulation is well established, but it is only one of several factors that are involved in the process, such as the homeostatic sleep drive, mental state, physical health, environment, etc.”

 

Journal reference: Sleep , DOI: 10.1093/sleep/zsac199

 

[Lilly_Pines]

The problem is two-pronged: too much artificial light in the evening and too little during the day.

 

I've found that the right amount of light in the bedroom before sleep is more like 2 lm than the 200 lm commonly available from small LED bulbs. Given that humans (with normal eyesight) are perfectly capable of navigating outdoors at night in minimal moonlight, there isn't really a good reason to use significantly more light than that indoors either. If your lights have sufficiently gradual dimming that your eyes have time to adjust it's really nice for the house to be no brighter than the outdoors. As a rough heuristic I'd say that if you can see colours, it's too bright.

 

Conversely, in daytime normal indoor light amounts of 200-1000 lux are equal to a very dark overcast day. I've found that the brightness of shadows on a sunny day (around 10,000-20,000 lux) is a good, comfortable amount but a bit expensive to replicate indoors so a more moderate amount of roughly 2,000-4,000 lux is a good goal for spaces people spend their mornings and early afternoons in. Everybody and their dog, building control included, will tell you that's too much light and they'll have various awful overilluminated offices etc. to support their argument but upon a closer inspection the claim falls apart.

 

Those "overilluminated" spaces are almost always lit with uniform brightness and colour temperature with no dynamics or proper variety to the lighting, which practically never happens in nature; an awful overcast day on a flat featureless plain is probably the closest it gets, except that the "overilluminated" indoor spaces probably have the exact same brightness and colour at 11:00 and 17:00. In any real outdoor space humans inhabit there is at least the variation between shadowed areas that get less skylight and bright areas that get more, along with the diurnal cycle. When the sun is shining you also get the difference between yellowish sunlight and bluish skylight.

 

If you replicate these conditions indoors by combining direct light at 4000-5000K and indirect light at 5600-6500K you'll likely find the effect of golden "sunlight" and bluish shadows very pleasant and almost no amount of light feels excessive as long as you ensure the right balance of brighter and darker spots and their positioning relative to yourself. (This is also likely to cure or at least significantly alleviate SAD, suffered by around 1/3 of the population in the UK.)

 

Now if you have >2000 lux during the day, gradually tapering down to 0.2-2 lux at night, I'd bet the effects on your sleep would be dramatically lower than keeping the normal amount of lights on long past sunset. The relatively bright and blue light during the day should ensure wakefulness and the dimmer, redder evening light should set the contrast appropriately.

 

Outdoor light is also usually too bright once it gets late, creating pools of illuminance surrounded by a stygian abyss. I like the idea of having a very small amount of light outside windows so that they aren't black panels of unknown but instead you can just about make out what's going on outdoors even with the (low amount of) lights on. Admittedly this gets more complex in public spaces that have to accommodate people with worse night vision at least until we get bionic eyes on the NHS or high-spec night vision gear at Specsavers for £30.

[Radian]

My kind of topic. 😍 The colour temperature of LED lamps is the most important parameter to me. The vast majority use blue or UV LED's to excite a phosphor to emit wideband light and are still very peaky at the blue end of the spectrum. They're fine for occasional task lighting, and I never use any that are over 3000K but I prefer using RGBW bulbs that are programmed to fade down to yellowish amber or deeper reds for the evening. This is the time of year people have lights on but curtains open at dusk and it amazes me how many people look like they're arc welding in their living rooms and bedrooms. Speaking of which, I literally get arc-eye in some illuminated spaces like supermarkets and public buildings. I do like pops of colour for contrast though. Especially outdoors, but then I've got pretty much unlimited numbers of prototype outdoor LEDs to call on. Couldn't agree more about illuminating what's outside the windows as it's pitch black around here otherwise.

[joe90]

I hate blue/ultra white lights, I much prefer dimmed/yellowy  lighting with the exception of work lights to do tasks.

[jack]

1 hour ago, Radian said:

This is the time of year people have lights on but curtains open at dusk and it amazes me how many people look like they're arc welding in their living rooms and bedrooms. 

 

Yes, we have 2700k lighting and try to keep it turned on as low as possible in the evenings.

 

Televisions can be really bad. Newer TVs (especially HDR) are massive and output an enormous amount of light across a huge proportion of your field of view. I have to turn ours down to the lowest brightness setting to watch it at night. If I don't, I find very bright scenes very painful.

[SteamyTea]

1 hour ago, jack said:

Televisions can be really bad

Why I got rid of mine nearly 30 years ago.

That, and I moved to the USA and found out about illegal downloading.

 

[BlackMountainBuild]

The area I’m building in (pray to the dread gods of planning) is dark skies, I was up there on site recently and the sky was so cloudy there was no moon or stars, no neighbours visible so no artificial lighting, couldn’t tell where the sky began and the earth ended, it was like being alone on the ocean or something, velve inky black as far as you could see - hadn’t seen it like that before, was somewhat disconcerting.