A bad night's sleep has a major impact on your day. We all know the things that can contribute to poor sleep patterns: stress, caffeine, our children, noise, our children (they warrant being listed twice!). But how much do you know about how light can impact your chances of getting a good night's sleep? This was a really interested insight for us so we'll summarize as best we can below.
"Light is perhaps the most powerful stimulus for our mental, physical health and for our performance in every endeavour" - Andrew Huberman
Not falling asleep? Stomach issues? Irritable? Feeling down? Keep reading ...
- The way we function is by way of our nervous system.
- Our nervous system links all organs to the brain and body (brain, spinal cord, spleen, heart, lungs, etc.).
- So the nervous system is, without question, the most powerful organ system in our body, acting like a conductor.
- Vision, which involves photons and light energy, is the way that the nervous system decides when to be alert and functional and when to be asleep.
So getting bright light in the morning is vital. Why?
- Every cell in our body is coordinated to a general hormonal signal.
- Hormones are chemicals that are released in one location in the body that go and act at other locations in the body.
- A key hormone for health is cortisol.
- We always hear about cortisol as a stress hormone, but every 24 hours there is going to be a peak in cortisol release.
- It activates your immune system in a positive way, provided you don't have too much cortisol throughout your day.
- This peak is going to happen no matter what.
- If you get light in your eyes early in the day, the peak will arrive early in the day.
- One other hormone signal that you've likely heard of is the hormone melatonin and it makes up feel sleepy.
- Light viewed by the eyes inhibits melatonin. So much so, that if melatonin levels are at their peak and you flip on a bright light in the washroom, in 10 or 15 seconds your melatonin levels will drop to 0.
- Truly a remarkable relationship to the outside world.
Getting light exposure early regulates your internal clock:
- Every cell in your body has a 24 hour clock
- However, every cell in your body has its own separate clock.
- The way these clocks are coordinated into coherent action is from a signal in the brain called the hypothalamus.
- The only way that signal can arrive properly is if you are getting light to trigger the hypothalamus to say, okay, get up!.
- Otherwise your body becomes a clock shop where every clock is on a different time and alarms are going off every 10 minutes.
- This is why many people have stomach issues when they travel. Cells in your body are falling out of sync.
One of the key findings in the field of biological psychiatry is that when the peak of cortisol doesn't derive early in the day, it starts drifting later and later and later in the day. People start getting mood issues, they start feeling irritable, and actually, it's a hallmark physiological signature of depression to have a late shifter cortisol peak.
- Many people report that just simply getting bright light exposure in their eyes early in the day, ideally sunlight corrects a number of these issues.
So a few big takeaways to positively impact your sleep:
- View light early in the morning, ideally outside sunlight.
- Starting at 9 or 10pm, begin dimming the lights in your environment.
- If on screens in the evening, dim the screens. You don't have to be worried about the type of lights, but rather about the brightness.
***All points come from Huberman & Shane Parrish on the Knowledge Project Podcast Episode #133