So, I like this quote that says:
“When you travel from America to Europe, your soul takes about three days longer to get there.”
And I know this is certainly true when I travel from here to Serbia, my home country. It does take me several days basically, to feel normal, to feel aligned with the population that’s living there. And this is because your clock takes a few days to get realigned with this new schedule.
And, if you think about this, this makes sense, right? So, for pretty much all of our history, except for a blink of an eye, in our evolutionary history, nobody had a way of hopping from one continent to the other in a matter of hours. We’re changing time zones so quickly, and in this case, nature’s not really keeping up with what we are capable of doing.
So, what is this clock? And why is it important to think about light?
The clock is a molecular oscillator, the details here are not important at all, I don’t want you to look at the names of these things on the board. But I want to point out that the clock is essentially the same in animals such as fruit flies, which my lab uses in our studies, and in mammals like mice or humans.
And the first glimpses of the clock, the components of the clock, and the way that it ticks were gained in the fly, actually. What I want to stress here is that the clock is tuned by light.
Some of the components of this clock are actually degraded, directly degraded by light. So, that results in the state of the clock essentially oscillating throughout the day and night.
You can imagine if the composition of the clock, if some of the components are degraded, the composition of the clock will change between day and night. And then the outputs of the clock between day and night will be different.
So, for instance, during the day, the state of your clock is such that you are suppressing production of melatonin, which is the hormone that helps you fall asleep, but also has other functions, such as anti-cancer and antioxidant properties.
So light. Let’s talk about blue light a little bit. When you’re outside during the day, you’re, of course, exposed to sunlight which consists of different wavelengths of light.
But the one that’s particularly important is blue light, because of its effect on our clock. Blue light also directly elevates your mood, it boosts your attention and your alertness.
So blue light during the day is very, very good, and I’d say that most of us don’t spend enough time in a bright light outside. You should be for 30 to 60 minutes outside in bright light, so put some sunscreen on and go outside.
The flip side of this is that when you come home at night I would dare guess that pretty much none of us spend the rest of the day when we come home, in darkness, and we’re not in tune with the natural light and dark cycles, right?
So, what we do normally is we use our computers, smartphones, tablets; we are in rooms that have high amounts of LED light. And, in particular, what’s really bad is that these devices are very, very rich in blue light.
So, what you’re doing, every evening, when you’re using these devices is you’re essentially tricking your clock into thinking that it’s still day. And since the clock during day and blue light suppress melatonin production, you’re essentially doing that at night.
Now, I’m not naive enough to suggest you never use your computer at night, I know I wouldn’t abide by that.
But one thing that you can do, is you can turn the brightness of your screen in the evening, you can download programs that filter some of the blue light or you can use glasses that block some of the blue light.
I have a little bit of news for you that maybe you’ll perceive as bad, but I think it’s actually very good, which is that you are very much like these guys.
So, this is a close-up of a fruit fly, and you may not like if I tell you that you are like these guys. But think about it for a second, this is very good for us because now we can use these animals as a model system to understand more about sleep biology, and how light influences our clock and our health, and this is what my lab is doing.
So, they sleep just like we do, they sleep at night. If we deprive them of sleep, then they crash the next day during the time they would normally be active. If we deprive them of sleep for a long time, they die; so sleep is very important for them.
The same genes that regulate sleep in humans regulate sleep in flies. And when they’re asleep they’re disconnected, at least to a large degree, disconnected from their environment, just like we are.
So, if these guys are sleeping, you need a stronger intensity stimulus to get them to react than when they’re awake. So same thing that happens to you of course, when you’re asleep.
Two people in my lab: a postdoc, Iris Titos Vivancos and a PhD student, Michelle Frank, are asking exactly what is this barrier that’s established in the brain that prevents sensor information from coming through during sleep?