Would life be significantly different if no light were detectable when closing our eyes?
Currently, if your eyes are closed you can still get a sense of the light around you, and moving your head around you can tell if you're moving it toward or away from a light source (barring maybe if you're outdoors and it's bright out all around you).
But what if when we closed our eyes it was like full blackout? Would blinking become disorienting? Could it mess up circadian rhythms? Something else? Or would it not really matter?
You can see your nose at all times, as it is within your field of vision at all times - but your brain filters it out, so what you actually "see" is a nose-free impression of your surroundings. It works like a movie editor that removes unwanted parts from raw footage before the movie is actually shown to the public.
If blinking were a total blackout for a fraction of a second, I'd wager the human brain would have developed a workaround to delete that / filter it out as well, so you wouldn't even notice a difference.
yeah, i wish.
I was gifted a big fat bulbous beak from my parents, it's half my vision!
I've got a narrow nose, and I still notice it all the time.
Already does. Persistence of vision. It's why some seconds seem longer when you look at a clock suddenly. Your brain fills in the missing "frames" with what it thinks should be there.
I'd sleep way better and wouldn't need blackout curtains
But then you wouldn't be able to naturally wake up in the morning, which is best triggered by light much as the release of melatonin is triggered by darkness.
I don't wake up to the light though
It helps with waking much as darkness does with sleeping, but it similarly is not going to be enough to overcome under sleeping or a sleep disorder.
Sure but I need help going to (and staying) sleep, not waking up. My natural wake up time is before the sun rises (430-5am)
Have you tried abusing prescription drugs?
Interestingly, you note that your natural wake up time is when the sun rises, but don't recognize that it might be because that's when the sun rises.
Interestingly, I wake up 2 hours before sunrise and noted my use of blackout curtains regardless.
Sounds like you have a relatively healthy sleep-wake schedule.
Most people need to work in the winter, too. It's still dark outside in the morning either way, whether my eyelids are translucent or not.
You can make it a lot easier to wake up in the winter months by getting a sunlight clock.
I would say most things would not be much different, but circadian rhythm is probably the most relevant part. If your eyes cannot sense sunlight in the morning,
your sleep will no longer be affected by daytime hours. Edit: your skin can also sense changes in light, it could potentially also detect sunlight in the morning if exposure is strong enough. Thanks @Repelle for the insight! Article: https://www.sciencedirect.com/science/article/abs/pii/S1389556721000022Our mind doesn’t really process the time we blink, whether light comes through or not. If we had it happen our entire life, I’m sure we’d probably adapt quickly to having a complete blackout when closing our eyes.
I vaguely recall a study from well over a decade ago where they used a light patch so that the only change in light for the sleeping participants would be on the skin and showed that circadian rhythm wasn’t dependent (solely, at least) on eyesight. Mind you this is a vague memory from a long time ago so take it with a grain of salt.
Not the article you were thinking of, but reinforces your point. https://www.sciencedirect.com/science/article/abs/pii/S1389556721000022
Tl;dr, there are light sensors, or at least light energy sensing mechanisms, in our skin.
There was a study of a guy who lived underground for months with no timekeeping devices. His only contact was with other researchers by telephone, and not often. His sleep schedule and length he’d stay awake got super wonky but he had no idea. So the complete lack of light certainly has an effect.
It would have a negative impact on your sleep-wake cycle, which relies on light and darkness. You would fall asleep more easily but struggle to wake up.
Nothing would happen. You blink for a fraction of a second.
Also, note that the eyelids of people with darker skin already pass less light than those of people with lighter skin. (That is the purpose of darker skin)