The science
The mechanism of a sheet eye mask is occluded hydration, and it is worth separating what that can and cannot do around the eye. Under a wet sheet the stratum corneum takes up water rapidly, and glycerin, present here at second position, holds that water in the outer layers after the sheet is removed; controlled measurements of skin hydration after sheet-mask use show a sharp rise that decays over a few hours. Because the periorbital skin is thin and fine lines there are often dehydration lines rather than structural wrinkles, this transient plumping produces a visible smoothing and a brighter appearance, since a hydrated, smoother surface scatters less light. That is the entire basis of the brightening claim. Dark circles, by contrast, arise from post-inflammatory or constitutional pigmentation, from the visibility of the vascular plexus through thin skin, and from tear-trough shadowing, none of which a humectant gel affects; ingredients with evidence for those problems, such as caffeine for vascular puffiness, vitamin K oxide, niacinamide or retinoids, are absent from this formula.
Milk protein extract and peach extract are the botanicals actually present. Hydrolysed milk proteins form a light film that improves skin feel and can modestly reduce water loss in the short term; there is no evidence for firming or brightening. Peach fruit extract contributes sugars and trace polyphenols. The pumpkin, watermelon and lettuce extracts described in the product marketing do not appear in the declared ingredients, and their claimed enzymatic exfoliation and vitamin content are therefore not relevant to this mask as sold. Arginine and allantoin add a small humectant and soothing contribution respectively.
The essential-oil fraction is the clinically important part of the list. Lemon, bergamot, orange and mandarin peel oils, geranium, clary sage and palmarosa oils together deliver limonene, linalool, citral, geraniol and citronellol, all of which are recognised fragrance allergens under EU cosmetic labelling, and the periorbital skin is among the most common sites for cosmetic contact dermatitis because of its thinness and the frequency with which products migrate toward the eye. Bergamot oil contains bergapten, a photoactive furocoumarin; at the low concentrations typical of a cosmetic fragrance blend the phototoxic risk is small, but it is a reason to prefer evening use or to follow with sunscreen. The absence of alcohol and the mild preservative system of hydroxyacetophenone, ethylhexylglycerin and hexanediol are points in the formula's favour; the decision to perfume an eye product this heavily is not.