A Science-Based Skincare Routine

The mechanisms behind cleansing, moisturizing, morning light, and sunscreen — and the routine I built from them

Last updated on May 11, 2026 13 min read Health

Why This Post Exists

One of the common questions I receive has nothing to do with AI. People ask me, what skincare products do you use?

It feels good when people see me embody K-beauty standards. I usually try to laugh it off. But when the question gets asked more than twice, I know it’s no longer just a compliment — they’re asking for real solutions to their own problem.

The honest answer is that the products matter much less than the principles. Most of what works is upstream of the brand on the bottle — water temperature, pH, timing, what you eat, when you see the sun. This is a written response to the recurring question, so I can send a link instead of repeating myself.

These principles are deeply embedded in the routine I’ve kept for 20+ years. I even carried the key items — cleanser, lotion, sunscreen — with me to military boot camp and used them every day in the tight window I had for personal time.

What follows is my actual routine paired with the research that justifies each step. Wherever possible I’ve cited the peer-reviewed source rather than the influencer who relayed it.

1. Cleansing

I don’t remember anyone teaching me how to wash my face properly, and I assume most people weren’t taught either. Below I lay out the overlapping face-washing tips from verified sources, and share YouTube videos of Korean dermatologists demonstrating the proper technique.

Twice daily — morning and evening. I use a hairband so I can clean the hairline without wetting my hair.

The four rules I follow:

Mildly acidic (약산성) cleanser — pH close to 5.5
Lukewarm water (미온수) — roughly the midpoint of the faucet
Half a dose of foam in the morning (water alone is not enough; a full dose is too much)
Pat dry with a towel — never rub

Why pH matters

Healthy skin sits at a surface pH of roughly 4.7, maintained by sebum, sweat, and the activity of filaggrin-derived amino acids. This acid mantle keeps barrier enzymes active, suppresses opportunistic bacteria, and stabilizes the intercellular lipid lamellae.

Conventional soaps land at pH 9–10. A single wash with high-pH soap measurably raises skin pH for hours, increases transepidermal water loss (TEWL), and impairs the lipid-processing enzymes (β-glucocerebrosidase, acid sphingomyelinase) that keep the stratum corneum intact.^1,2

Key point: Choose a mildly acidic (약산성) cleanser. “Squeaky clean” is the sound of your acid mantle being stripped.

Why lukewarm — and why the “hot then cold” myth is wrong

You’ll hear that you should wash with hot water to “open the pores,” then rinse with cold water to “close them.” Pores have no muscles. They don’t open or close in response to temperature.

What hot water does do is solubilize the stratum corneum’s intercellular lipids — the same ceramides and cholesterol esters you’re trying to preserve. Cold water doesn’t undo that damage; it just adds vasoconstriction and irritation on top.

Use lukewarm water from start to finish.

Don’t scrub — lay the foam down

Mechanical friction is the enemy of the stratum corneum. The Korean phrase I use as a cue is 거품을 얹는다는 느낌으로 — “as if you’re laying the foam on top.” Whip the cleanser into a real lather with water first, then place it on the face and let the surfactants do the work. After rinsing, pat dry — don’t rub.

Common mistakes

Habit	What’s actually happening
Hot → cold rinse to “open and close pores”	Pores have no muscles; the hot phase strips lipids
Scrubbing “thoroughly into every corner”	Mechanical disruption of the stratum corneum
Morning rinse with water only	Overnight sebum and biofilm aren’t water-soluble
Vigorous towel-drying	Friction-induced micro-tearing

2. Moisturizing

Within 10 seconds of patting dry, I apply a hydrating essence, then a lotion on top. Aestura is a cosmeceutical brand from Amorepacific, and its separate medical-grade lineup is often preferred by dermatologists. I’ve been using the consumer-grade retail products for 5+ years.

Essence: 아토베리어365 하이드로 에센스 (Atobarrier 365 Hydro Essence)
Lotion: 아토베리어365 로션 (Atobarrier 365 Lotion)

The 3-minute rule (and why I shortened it to 10 seconds)

The American Academy of Dermatology’s atopic dermatitis guidelines recommend applying moisturizer within 3 minutes of bathing — the “soak and seal” method. The mechanism is straightforward: after cleansing, the stratum corneum is transiently hyperhydrated, and that water is evaporating quickly. Applying an occlusive/humectant on damp skin traps the water inside instead of letting it escape into the air.

I shorten that window to 10 seconds because the math gets worse the longer you wait — TEWL is highest immediately post-cleansing and decays exponentially.³

Key point: Apply the first hydrating layer while your skin is still damp, not dry.

Why ceramides, not just water

A moisturizer that’s only humectant (glycerin, hyaluronic acid) pulls water into the stratum corneum but doesn’t fix the leak. Ceramides are 30–40% of the intercellular lipid matrix that holds the skin barrier together; the Atobarrier line is formulated around ceramide NP and a cholesterol/fatty-acid blend that mimics the natural lipid ratio.

Topical ceramide-containing moisturizers have been shown in randomized trials to restore barrier function and reduce TEWL in damaged or atopic-prone skin — performance closer to a barrier repair product than a basic emollient.^4,5

Neck and eye care

These are the areas a lot of people miss. As people age, the neck and the skin around the eyes are the parts that aren’t easily covered by makeup. Use extra moisturizer to build a sufficient hydration barrier in both. Well-moisturized neck and eye areas pay off over time.

3. Morning Sunlight

This is the step nobody asks about, but it’s the one I’d give up last.

Wake up 10 minutes before local sunrise
Walk to a nearby park (now: a rooftop with unobstructed sky)
Get 5–10 minutes of low-angle sunlight directly on the face

The circadian half

The intrinsically photosensitive retinal ganglion cells (ipRGCs) in your eyes use the pigment melanopsin, which is maximally sensitive to short-wavelength light around 480 nm. Bright morning light signals “this is daytime” to the suprachiasmatic nucleus, advances melatonin offset, anchors core body temperature rhythm, and raises evening melatonin onset — i.e., you sleep better that night because you got light this morning.

You don’t need to stare at the sun. Ambient sky brightness at sunrise (~10,000+ lux in open sky vs. ~500 lux indoors) is the active ingredient.^6,7

The photobiomodulation half — and why low angle matters

When the sun is low on the horizon, sunlight travels through a much longer path of atmosphere. UVB (the burning, vitamin-D-synthesizing wavelength, ~290–315 nm) is largely scattered and absorbed out before reaching you; longer wavelengths — visible red and near-infrared (~600–1100 nm) — pass through.

That’s the same wavelength band as the red light therapy panels used in dermatology clinics. The proposed mechanism is photobiomodulation: red/NIR photons are absorbed by mitochondrial cytochrome c oxidase, dissociating inhibitory nitric oxide, transiently increasing ATP production, and triggering mild reactive-oxygen-species signaling that upregulates collagen synthesis and downregulates inflammation.

Randomized trials of red/NIR exposure have shown improvements in collagen density, fine lines, and skin roughness at doses well within what sunrise-window exposure provides.^8,9,10

Key point: Sunrise sunlight is a high red/NIR-to-UV ratio. Midday sunlight is the opposite. Treat them as different doses of different drugs.

4. Sunscreen

Different time of day, different rules.

Mandatory if total direct sun exposure for the day will exceed 20 minutes
Regardless of weather — overcast, cloudy, doesn’t matter

Product: 자작나무 수분 선크림 (a Korean SPF 50+ formula).

Why “cloudy” is not a free pass

Cloud cover blocks visible light far more than it blocks UVA. On a moderately overcast day, up to 80% of UVA still reaches the ground.¹¹ UVA penetrates deeper into the dermis than UVB, drives photoaging via reactive oxygen species, and you don’t feel it the way you feel UVB burning — there’s no sensory feedback to tell you it’s working on you.

If you can see your shadow at all, you’re getting UV.

Why I prefer the Korean version

The Korean and US formulas of “the same” sunscreen are often genuinely different products. The US FDA has not approved newer-generation UV filters — Tinosorb S, Tinosorb M, Uvinul A Plus, Mexoryl SX/XL — that have been standard in Korea, Japan, the EU, and Australia for over a decade. These newer filters are:

More photostable (older filters like avobenzone degrade in UV — i.e., the protection drops while you’re wearing it)
Broader-spectrum, particularly across UVA1 (340–400 nm), where older US-available filters under-perform
Often less irritating and less endocrine-disrupting in the published literature (oxybenzone is the canonical concern here)

The FDA’s 2019 proposed rule deferred most organic filters to “additional data needed,” leaving zinc oxide and titanium dioxide as the only categorically GRASE actives.¹² Korean SPF 50+ formulations using Tinosorb S routinely outperform US drugstore options on UVA-PF benchmarks at comparable SPF.

Key point: The bottle might say “SPF 50+” on both sides of the Pacific, but the filter technology inside is a regulatory generation apart.

5. Breakfast

The cheapest skincare product is what you put on your fork. My standard:

2 boiled eggs
A handful of grape tomatoes
A mixed nut blend (almonds, walnuts, pumpkin seeds)
An apple

This isn’t arbitrary. Each item is there for a reason.

Food	Active component	What it does
Boiled eggs	Complete protein, biotin, choline, lutein/zeaxanthin	Substrate for keratin/collagen synthesis; retinal carotenoids
Grape tomatoes	Lycopene	Quenches UV-induced singlet oxygen; reduces UV erythema
Almonds	Vitamin E (α-tocopherol) + monounsaturated fat	Lipid-phase antioxidant; dietary fat vehicle for lycopene absorption
Walnuts	Omega-3 ALA + polyunsaturated fat	Anti-inflammatory; membrane phospholipid substrate; fat vehicle for lycopene
Pumpkin seeds	Zinc + unsaturated fat	Cofactor for wound healing, MMP regulation; fat vehicle for lycopene
Apple	Polyphenols, vitamin C, fiber	Antioxidant + cofactor for collagen hydroxylation

The most striking single result here is dietary lycopene: in a controlled trial, 10–12 weeks of tomato paste intake reduced UV-induced erythema by roughly 40% compared to control.^13,14,15 That’s not topical — that’s eaten photoprotection, working from the inside.

Lycopene is lipophilic — it’s a 40-carbon hydrocarbon carotenoid with zero hydroxyl groups, which makes it one of the least water-soluble micronutrients in the human diet. To get out of the tomato matrix and into your bloodstream, it has to partition into mixed micelles in the small intestine, which only assemble in the presence of dietary fat and bile acids. Eat tomatoes alone, on an empty fat-free stomach, and most of the lycopene passes straight through you.

How much fat changes the answer. Controlled feeding studies have shown that adding as little as ~5–10 g of fat to a tomato/carotenoid meal increases plasma carotenoid response severalfold versus a fat-free meal — and that the effect is bigger for the more lipophilic carotenoids like lycopene and β-carotene than for less hydrophobic ones like lutein.^16,17

That’s why the nuts aren’t a side dish in this breakfast. A small handful of almonds, walnuts, and pumpkin seeds delivers roughly 10–15 g of unsaturated fat alongside the tomatoes — enough to fully solubilize the lycopene into micelles and unlock the photoprotection trial endpoint above. The eggs do double duty here too: the yolk contributes another ~5 g of fat plus phospholipids that further enhance micellar incorporation.

Key point: Tomatoes without fat are a partial dose. The almonds, walnuts, pumpkin seeds, and egg yolk are the delivery vehicle that makes the lycopene bioavailable.

Practical corollary: if you swap the breakfast for fat-free tomato juice and an apple, you’ve kept the lycopene in the meal but thrown away most of the absorption.

What I Don’t Do

A short, deliberately negative list — because the absence of bad inputs matters as much as the presence of good ones.

No actives stacking. No retinol, no acids, no vitamin C serums, no exfoliants. The barrier-first approach makes most of these unnecessary, and at my age the upside is small relative to the irritation cost.
No physical exfoliation. Scrubs, brushes, and grainy cleansers all damage the stratum corneum faster than skin can rebuild it.
No fragrance-heavy products. Fragrance is the single most common contact-allergen class in dermatology referrals.
No “pore-minimizing” anything. Pores are not muscles; they are not closable.

Sources I Trust

The Korean dermatologist YouTube channels I learned the cleansing technique from are worth watching even if you don’t speak Korean — the demonstrations are visual:

피부심: 피부과전문의가 직접 보여주는 완벽한 세안법 — board-certified dermatologist walkthrough of cleansing technique
30대 피부과의사의 모닝케어루틴 — a dermatologist’s own morning routine
Cleansing tips from a Dermatologist (subtitled) — low-irritation cleansing for sensitive skin

The Compressed Version

If you want one paragraph: Use a mildly acidic cleanser with lukewarm water, pat dry, moisturize with ceramides within 10 seconds. Get 5–10 minutes of sunrise sunlight on your face. Wear broad-spectrum sunscreen (preferably with newer UV filters) any day you’ll be outside more than 20 minutes, cloudy or not. Eat tomatoes, eggs, nuts, and an apple for breakfast. Skip the rest.

The products are interchangeable. The principles aren’t.

References

Skincare Health Routine