Light Color/Intensity and Sleep

Fellow QSers,

For the past couple years, I’ve been studying how circadian-timed light systems influence our health with the dLUX Light Lab at Drexel University in Philadelphia. The theory in a nutshell: Light is the primary influencer of our biological clock, or circadian rhythm. Blue-colored light triggers the retinal ganglion cells, which entrain the Suprachiasmatic Nuclei (SCN) to the external environment. Among other functions, the SCN tells the pineal gland when to release melatonin. The SCN operates on its own but synchronizes to the natural pattern of light and dark over about 24 hours.

Artificial lighting has enabled many of the advances and conveniences we now take for granted, but by allowing us to have day at night, it interferes with the proper SCN entrainment, exacerbating (and potentially causing) a variety of conditions, reducing the quality of our sleep, and reducing energy levels during the day. Bright, white light during the day and little to no light (or dim reddish light) at night have been found to optimally promote entrainment. This is intuitive, given that the sun follows a similar pattern and that the retinal ganglion cells, which provide input to the SCN, are not sensitive to higher wavelengths of light (such as red).

Now that many of the devices and methods popularized by the QS community and others (actigraphy, PVT, heart rate variability, etc.) can reasonably gauge our sleep quality, reaction time, stress levels, and more, I believe that light color and intensity should not only vary based on the geophysical cycle, but also in a way that is adaptive to our own biomarkers. For example, someone exhibiting sleep inertia (grogginess upon waking) may be getting too much bright light too early in the morning, potentially interrupting slow-wave sleep. Two fixes may be possible: using a combination of motorized blackout curtains and color-tunable lights to delay morning light, and/or lowering the light intensity/shifting toward red earlier in the evening to discourage sleep latency. My master’s thesis involves using a variety of biomarkers to identify which light states promote various sleep conditions, and designing an algorithm that adaptively takes these biomarkers into account to adjust color-changing lights and blackout curtains.

I am developing a light control system that interacts with color-shifting lights such as the Philips Hue and motorized shades to adaptively control light levels based on geophysical patterns. The system evolved out of a need my research lab encountered – no light control system was nearly powerful enough for us to achieve what we wanted – but I also realized that others might be able to take advantage of this technology. I plan to have the first version on the market in 6-8 months. Early versions will mimic the patterns of the sun automatically, and later software updates will incorporate the adaptive algorithms I am testing with the lab.

I’ve seen several QS studies involving light and sleep, including this one. If adaptive circadian light control beyond the computer screen were affordable and simple enough to use, would you be interested in using such a system in your daily life? If so, would you mind spending less than 5 minutes answering a few (anonymous) questions about your health, habits, and interest in a circadian light system? The survey link is here.

Is anyone else interested in more deeply understanding light in relation to sleep?

More to come.

Hi Greg,

I have also been looking into this more recently. I’ve had a delayed sleep phase for a long time now. After college I tried melatonin supplementation and to have better sleep hygiene, but I have never found anything that works really well for me. I’m a PhD student right now so I can get away with setting my own hours, but I also recently suffered from a minor head injury and now it takes me over an hour to fall asleep, even when I go to bed whenever I feel tired. My schedule is also getting more full in the afternoon/evenings, so I would like to shift my sleep schedule earlier.

I just read the book Internal Time and it reminded me about a talk that was given at a QS Boston show & tell a while back. I just ordered myself a pair of Uvex glasses to try out. I also have a Phillips wake light, but found it certainly isn’t a panacea. I’ve had a beddit for a while now so I’m planning to use that to help test the effect of any interventions on how long it takes me to fall asleep.

I filled out your survey and would be happy to chat more as well.

Hi Maggie,

Great that some of us are on the same wavelength! I checked out your website, and it looks like you’re doing a lot of work with wearable polysomnography sensors. I’m starting to work with some people at my university to better understand EEG, ECG, fNIRS, etc. It’s all pretty exciting stuff.

I think the way forward with a lot of sleep-improving technologies is automatically interpreting various biomarkers and using environmental states and/or advanced drug delivery to optimize them (with a lot more focus on the former). I don’t believe changing light states alone are a panacea, but when your environment is adaptive, it can be quite a bit more helpful than just guessing.

I’m going to read Internal Time - thanks for the tip! Another easy, but comprehensive read on the subject is Sleep: A Very Short Introduction, although I imagine there is a lot of overlap. I also just picked up a pair of orange glasses, something I’ve been meaning to do for quite a bit. That QS Boston talk was very convincing, and I can’t wait to run some experiments with the glasses.