We all know how it feels to have drooping eyelids after a long day. It happens for the same reason we feel like slouching down on the sofa, putting our feet up and leaning our head against someone else’s shoulder when we’re tired– muscle fatigue. Throughout the day our eyelids are kept out of your eyes’ way through a muscle over each eye (the levator palpebrae superioris muscle, to be specific!). And, like any other muscle in constant use, it gets tired.
More than that, as our body readies for sleep, several changes take place within the body: a hormone called melatonin increases, body temperature decreases and blood pressure lowers. It seems to be that the feeling of heavy eyelids may just be another hard-wired change – like a tendency to yawn – that happens when we are tired.
Some individuals are more prone to this sensation than others – say, if your eyelids are particularly large, you may suffer from allergies, sinus infection and/or swelling through sun exposure.
Rubbing your eyes can buy you some time as it increases blood flow to the eyelid muscles giving them a new surge of energy. The only ultimate cure however is to actually get some shut-eye. Match sticks will only last so long.
Answer by Isabel Hutchison
Image Source: Unseeing By Pekka Nikrus, on Flickr