Lying flat lets fluid pool in the thin eyelid skin, so you wake puffy and deflate by mid-morning.
Salt, alcohol, crying, and short sleep all add fluid; allergies add inflammation. The NHS maps swollen, itchy, or sticky eyelids to allergy, blepharitis, or conjunctivitis, and blepharitis specifically causes swollen, itchy lids with morning crusting, treated with daily lid washing. Cold compresses, a slightly raised pillow, and lighter late-night salt and alcohol handle the fluid version. Pain, fever, vision changes, one-sided swelling, or any lip, tongue, or breathing involvement escalates it.
What to do
Common questions
Why do I wake up with swollen eyes?
Morning puffy eyes are usually fluid, plain and simple. Lying flat for hours lets fluid redistribute into the loose, thin skin around your eyes, where it shows up as swelling that fades over the first hour or two of being upright. What makes it worse: salty food the night before, alcohol, crying, poor sleep, allergies, and sleeping face-down. The NHS's eyelid problems page maps an itchy, flaky, sticky, or swollen eyelid to allergy, blepharitis, or conjunctivitis, so the pattern matters: both eyes, mild, gone by mid-morning, equals fluid; one eye, redness, itch, crusting, or stickiness, equals something worth a pharmacist's eye. Blepharitis, per the NHS, causes swollen, itchy eyelids with crusts at the lash roots and lids that stick together in the morning, and it is managed with daily eyelid washing. Home fixes for fluid puffiness: a cold flannel or chilled gel mask for a few minutes, sleeping slightly propped up, going easy on late-night salt and alcohol, and treating your allergies. See a GP promptly for swelling with pain, fever, vision changes, or one bulging eye, and if facial swelling ever comes with lip or tongue swelling or breathing trouble, treat it as an emergency allergy reaction.