Do we use muscles to close our eyes, e.g. to blink, to sleep, to keep out foreign objects, or do we use them to open our eyes, as it seems when we wake up? That is, are they naturally closed so that they have to be muscularly opened? It feels this way when we fall asleep. Or are our eyelids simply neutral devices that are moved around as needed by muscles that open and close them?
All I know for sure is that dying with eyes open or closed are both valid things.
Assuming that recent death completely neutralizes muscle contraction, that tells me that human eyelids stick where they’re put.
Pretty sure that is mostly correct. There are no tendons causing elastic recoil, so no real “neutral state”. But “rest” still seems to be closed or at least mostly so.
During anesthesia a slim majority of eyes completely close but roughly 40% stay open at least partially (hence the need to tape eyes shut during surgery to protect from corneal abrasions).
Staying fully closed during sleep is using some muscular activity to keep them so, and staying open while awake also requires some muscular activity
My aunt had a stroke a few years ago which left her unable to open one of her eyes. So clearly there must be some nerve impulse to do that.
I don’t think I have ever heard anyone say, “I’m so tired I can’t keep my eyes shut.” so I’m thinking naturally shut.
@suranyi, there clearly are nerve impulses involved to open an eye … and nerve impulses involved to shut an eye. In fact some people after strokes cannot completely shut their eyes, leading to risk of damage.
@Czarcasm, if you define “at sleep” as “naturally” yes, but there are in fact impulses to muscles occurring in sleep giving a message to keep the eyes shut. I’d think “naturally” means the position they’d assume without active muscle involvement
When I consciously go into relaxed mode, my eyes are more than 50% closed. Maybe 75%? I have dabbled in deep relaxation and breathing techniques. I find it is a conscious thing to keep the eyes closed for me when doing such things. Not caring leaves them partially open. But that interferes with the deeper relaxation if there is perceptible light and motion. I have to make the decision and I suppose effort to close them. But after a time, it seems the effort is not required.
I guess there are variations to the situations that change the eyes closed effort/trigger? Maybe the primal setup is quickly modified and made more complex by learned experience in infancy. And maybe even later?
According to my dry eye doctor, I sometimes don’t close my eyes all the way when I sleep. He suggested that there are exercises that I might want to pursue if my eyes don’t improve based on other parts of the treatment plan.
I’m not quite sure what the implications are, but it seems relevant to the thread, at least.