Medik8 Sleep Glycolic Review: 10% Overnight AHA Exfoliant
The Verdict
Sleep Glycolic is a considered, higher-strength take on glycolic acid: a genuine 10% concentration held back by an encapsulation system so it releases gradually overnight rather than all at once. Used at the stated 2-3 times a week, leave-on, it suits normal, combination and oily skin working on texture, dullness and uneven tone — but Medik8 is explicit that this one isn't formulated for sensitive or reactive skin, so that's worth taking seriously rather than testing to find out.
Medik8 Sleep Glycolic™ | Overnight AHA Peel | 30ml
£39.00
Medik8 Sleep Glycolic is a 10% glycolic acid overnight leave-on treatment, used 2-3 times a week, built around encapsulation technology that releases the acid gradually while you sleep. It's positioned as a step up from a daily glycolic toner — a genuinely higher acid concentration, but delivered in a way designed to reduce the sting and redness that a 10% AHA would normally bring. Here's what's actually in the formula, how it's meant to be used, and who Medik8 says it does and doesn't suit.
Quick facts
| Detail | What it is |
|---|---|
| Product type | Overnight leave-on AHA exfoliant |
| Format | 30ml |
| Key active | 10% Active Glycolic Acid |
| Delivery system | Crystal encapsulation technology (time-release) |
| Also contains | Korean Clover Extract, Glycerin |
| pH | 3.5 |
| Suits | Normal, combination and oily skin — not formulated for sensitive or reactive skin |
| How often | 2-3 times weekly, evening, leave-on |
| Price band | Mid-to-premium — see the product page for current pricing |
What's actually in the formula
The headline active is glycolic acid, an alpha hydroxy acid (AHA) derived from sugar cane. It's the smallest AHA molecule, which is what lets it penetrate skin more readily than larger acids like lactic or mandelic — useful for effective exfoliation, but also why a 10% concentration applied undiluted can be a lot for skin to handle in one go. Medik8's answer to that trade-off is what it calls crystal encapsulation technology, a delivery system that houses the acid so it's released gradually overnight rather than hitting skin at full strength on contact. Cyclodextrin-type carriers are commonly used for this kind of encapsulated, time-release delivery in skincare — see our cyclodextrin glossary entry for how that technology generally works.
Supporting the acid are Korean Clover Extract and glycerin. Glycerin is a well-established humectant, drawing moisture into the upper layers of skin to help offset any dryness from the acid. Korean Clover Extract is included as a conditioning, skin-supporting ingredient rather than an active exfoliant in its own right — the exfoliation work here is done by the glycolic acid alone. The formula sits at pH 3.5, an effective pH range for glycolic acid to work at.
Texture and how it feels
It's a lightweight, silky leave-on formula that absorbs without a sticky residue. Some tingling on application is normal for a 10% AHA and typically settles within a few minutes; it isn't designed to cause visible flaking or downtime the way an in-clinic peel might. Because it's a leave-on rather than a rinse-off toner, it stays on skin overnight, which is part of why frequency matters more here than with a daily-use exfoliating toner.
Who it's formulated for — and who it isn't
Medik8 positions Sleep Glycolic for normal, combination and oily skin working on the appearance of dull or uneven tone, rough texture, fine lines, visible congestion and enlarged-looking pores. It's also positioned as a way to help maintain results between in-clinic peel treatments, for anyone already having professional facials or peels.
Medik8 states this product is not formulated for sensitive or reactive skin. That's a meaningful distinction from some of the brand's gentler exfoliating toners — at 10%, even with encapsulation, this is a stronger AHA product, and it's worth taking that guidance at face value rather than trialling it if your skin reacts easily to actives. If you're not sure whether your skin falls into that category, our team can talk it through before you start.
How to use it in a routine
Apply in the evening, on cleansed, dry skin, 2-3 times a week rather than nightly — this is a leave-on treatment, not a daily step. As with any AHA, avoid combining it in the same routine as other exfoliating acids or vitamin A products on the same night; spacing actives out across the week is what keeps a routine like this comfortable rather than overwhelming for skin. Broad-spectrum SPF the next morning matters more than usual, since AHAs increase sun sensitivity.
If you're building this into a fuller routine, Medik8's Balance Moisturiser with Glycolic Acid Activator is designed to complement glycolic acid use, and it's worth thinking about how Sleep Glycolic sits alongside any other exfoliant already in your cabinet — our Press & Clear review covers Medik8's BHA toner if you're weighing up which exfoliating step fits your skin, rather than stacking both without spacing them out.
Pregnancy and breastfeeding
If you're pregnant or breastfeeding, please contact our team for advice before use.
Frequently asked questions
Can I use Sleep Glycolic if I have sensitive skin?
Medik8 states this product isn't formulated for sensitive or reactive skin. If your skin is reactive or you're unsure, our team can suggest a gentler alternative rather than have you find out by trial and error.
How often should I use it?
Medik8's own guidance is 2-3 times a week, applied in the evening as a leave-on treatment — not nightly, and not layered under other exfoliating acids on the same evening.
Will it make my skin peel or flake?
It's designed for visible improvement without the downtime of a traditional in-clinic peel. Some tingling on application is normal for a 10% AHA and usually settles within minutes; if you experience persistent redness, stinging or flaking, stop use and contact our team.
Can I use Sleep Glycolic alongside Crystal Retinal or another vitamin A product?
Not on the same night. Combining an AHA with a vitamin A product without spacing them out across the week is one of the more common causes of irritation, regardless of brand — our team can help you build a sequence that works for both.
Can I use this if I'm pregnant or breastfeeding?
If you're pregnant or breastfeeding, please contact our team for advice before use.
What's the difference between Sleep Glycolic and a glycolic toner?
A toner is typically a lower-strength, rinse-or-wipe-on step used more frequently. Sleep Glycolic is a genuine 10% concentration, left on overnight and used just 2-3 times a week — it's a stronger, more targeted treatment rather than a daily habit product.
The Skintique Academy view
Sleep Glycolic is a straightforward, well-considered way to bring a genuinely effective AHA strength into a routine without the commitment of an in-clinic peel — the encapsulation approach is a sensible answer to the usual trade-off between concentration and comfort. It suits normal, combination and oily skin working on texture, tone and the appearance of ageing, used at the stated 2-3 times weekly. It's not for everyone, though — Medik8's own guidance rules out sensitive and reactive skin, and that's worth respecting rather than testing. As ever, if you're pregnant, breastfeeding, or unsure how it fits alongside other actives in your routine, our team is here to help — just get in touch.