There was a very interesting interview on the Sleep4Performance podcast of Professor Sean Cain of Monash University, by Dr. Ian C. Duncan regarding light and the response of the human circadian system. I found there was quite a bit of practical information in this interview, and it’s worth a listen. Some of the interesting takeaways:

Did you know that hamsters are often used in sleep research? They are nocturnal and have a very strict circadian system response, so are useful for such research.

Our bodies like patterns and adjust well to them. My note: this is especially important in keeping a similar wake-up time every day

Exercise isn’t necessarily disruptive to our internal clock. Studies were performed with people on a 20-hour cycle and exercise was performed in different manners at different times, but the internal clock didn’t disrupt.

Relationship To Depression

Exercise increases the body’s responsiveness to light and can be very useful to elevate mood and decrease depression.

Exercise can be anti-depressive and help the circadian system better sync to the day.

Bi-polar individuals tend to be hyper-sensitive to light, and this can help explain their excessive time spent awake and some mania. Light therapy might be useful to help in treatment.

Choosing fatty foods after being sleep deprived might not just be because we’re making a bad choice and are fatigued – it could be a mechanism the body uses to recover from sleep deprivation. It’s an interesting route for further study.

People working night shifts don’t necessarily adjust to this odd schedule. They in fact learn to accept a new baseline “norm” of feeling lousy.

Wearables And Sleep Apps

Most sleep apps and wearables are sh*t.

Trying to predict your REM time and wake up at the end of REM is futile (good luck trying to be accurate in that prediction) and cutting your sleep short based upon such a prediction isn’t the best way to obtain good sleep. You’re better off sleeping longer and waking up naturally.

There is a large disconnect between the actual science and marketing of wearables and sleep apps.

Small Light Is A Big Disrupter

Exposure to only 30 lux of light (small nightstand lamp) can lead to 50% reduction in melatonin for many individuals.

A study showed using an iPad before bed (40-50 lux of light) delayed sleep onset of young healthy individuals by 10 minutes, which is quite significant. My note: points to the importance of eliminating electronic use before bedtime and creating a dark sleep environment.

Impact of light is not only important to sleep, but most importantly it impacts the circadian system and cascades down to impact many other body systems.