No. 6 Deep Sleep Mask Serum
No. 6 Deep Sleep Mask Serum
Product Description
Product overview
A lightweight, intensely hydrating serum powered by 63% Iceland Glacier Water and a 5-layer Hyaluronic Acid Complex. Clinically proven to hydrate skin up to 2.5mm deep and maintain moisture for 48 hours, this overnight treatment transforms dry, dull skin into a plump, dewy, glass-skin glow by morning.
63% Iceland Glacier Water
Mineral-rich water base sourced from Iceland, providing deep hydration and essential minerals instead of purified water.
Texture & feel
SENSORY63% Iceland Glacier Water
Mineral-rich water base sourced from Iceland, providing deep hydration and essential minerals instead of purified water.
5-Layer Hyaluronic Acid Complex
Multiple molecular weights of HA penetrate different skin layers for comprehensive, long-lasting hydration up to 48 hours.
Niacinamide Brightening
Vitamin B3 helps brighten skin tone, minimize pores, and strengthen the skin barrier while providing moisturization.
Antioxidant Botanical Extracts
Turmeric, Eggplant, Holy Basil, and Neem extracts provide anti-aging benefits and protect against free radicals.
Safety & compatibility
SAFENo retinoids, salicylic acid, hydroquinone, or chemical sunscreens. All ingredients are considered safe during pregnancy and nursing.
Contains Polyglyceryl-10 Laurate which may not be FA-safe for some. Many users with FA-prone skin report no issues, but patch test recommended.
Rating 1/5. Formula is lightweight and non-pore-clogging. Most ingredients have 0 comedogenicity rating.
Alcohol-free, fragrance-free, and essential oil-free formula. Contains soothing ingredients like Panthenol and Dipotassium Glycyrrhizate.
Ingredient breakdown
INGREDIENTSIceland Glacier Water 63%Key Base
Mineral-rich water sourced from Iceland's glaciers, replacing purified water as the product base. Provides essential minerals and superior hydration compared to regular water.
- Function: Hydrating base rich in minerals
- Benefits: Deep moisture replenishment, improved skin plumpness
5-Layer Hyaluronic Acid ComplexProven
A sophisticated blend of five forms of hyaluronic acid at different molecular weights, ensuring hydration reaches multiple skin layers from surface to deeper dermis.
- Sodium Hyaluronate: Standard HA salt for surface hydration
- Hydrolyzed Hyaluronic Acid: Low MW for deeper penetration
- Hyaluronic Acid: Classic HA for mid-layer moisture
- Sodium Hyaluronate Crosspolymer: 5x water-binding capacity of regular HA
- Hydrolyzed Glycosaminoglycans: Supports natural HA production
Niacinamide (Vitamin B3) 2.5-3.8%Proven
A multi-functional skincare superstar that brightens skin, minimizes pores, regulates sebum, and strengthens the skin barrier.
- Clinical Evidence: Proven to reduce hyperpigmentation at 2-5% concentration
- Barrier Support: Increases ceramide synthesis for stronger skin
- Anti-Aging: Helps reduce fine lines and improves skin elasticity
Panthenol (Pro-Vitamin B5)Proven
A gentle, soothing ingredient that attracts and retains moisture while supporting skin barrier repair and wound healing.
- Moisturizing: Humectant that draws water into skin
- Soothing: Anti-inflammatory properties calm irritation
- Comedogenicity: 0 - non-pore clogging
Adenosine 0.15-0.55%Proven
A cell-communicating ingredient with anti-aging benefits, helping improve skin firmness and reduce the appearance of fine lines.
- Anti-Wrinkle: KFDA-approved anti-aging ingredient in Korea
- Cell Signaling: Promotes collagen production and wound healing
- Barrier Support: Helps strengthen skin's natural defenses
Aquaxyl ComplexPromising
A trio of Xylitylglucoside, Xylitol, and Anhydroxylitol that optimizes the skin's water reserves and strengthens the moisture barrier.
- Components: Xylitylglucoside, Xylitol, Anhydroxylitol
- Function: Increases NMF (Natural Moisturizing Factors) in skin
- Studies: 3% Aquaxyl shown to improve dry, cracked skin after 1 month
39 ingredients
Glacial Water (63%), Butylene Glycol, Propanediol, Glycerin, Niacinamide, 1,2-Hexanediol, Purified Water, Chlorella Vulgaris Extract, Xylitylglucoside, Sodium Hyaluronate, Hydrolyzed Hyaluronic Acid, Xylitol, Melia Azadirachta Leaf Extract, Melia Azadirachta Flower Extract, Coccinia Indica Fruit Extract, Aloe Barbadensis Flower Extract, Solanum Melongena (Eggplant) Fruit Extract, Ocimum Sanctum Leaf Extract, Corallina Officinalis Extract, Curcuma Longa (Turmeric) Root Extract, Hyaluronic Acid, Glycereth-26, Panthenol, Pentylene Glycol, Glucose, Sodium PCA, Anhydroxylitol, Fructooligosaccharides, Fructose, Polyglyceryl-10 Laurate, Sodium Citrate, Dipotassium Glycyrrhizate, Sodium Hyaluronate Crosspolymer, Ethylhexylglycerin, Adenosine, Hydrolyzed Glycosaminoglycans, Citric Acid, Benzyl Glycol, Tocopherol, Xanthan Gum
Where it fits in your routine
ROUTINEUse after toner/essence. Can be used as the last step at night for an overnight mask effect. Layer under moisturizer for extra hydration.
How to use
HOW TO USECleanse & Prep
Start with clean skin. Apply toner if desired to prep skin for better absorption.
Dispense Product
Pump 2-3 times onto fingertips. A little goes a long way with this watery formula.
Apply & Pat
Gently spread across face and neck. Pat lightly to aid absorption. Works best on slightly damp skin.
Layer (Optional)
For intense hydration, apply a thin first layer, let absorb, then add another layer. Follow with moisturizer or use alone as an overnight mask.
Who is it for?
WHOPerfect for you if:
- You have dry, dehydrated, or dull skin
- You want intense hydration without stickiness
- You're looking for a lightweight overnight treatment
- You prefer fragrance-free, gentle formulas
- You want that "glass skin" glow effect
- You're pregnant or nursing (safe formula)
- You need to repair a compromised moisture barrier
Consider alternatives if:
- You have confirmed fungal acne and react to laurates
- You prefer thick, occlusive sleeping masks
- You want anti-aging actives like retinol
- You're looking for oil control or mattifying effects
- You need targeted acne treatment
Skin type compatibility
SKIN TYPESPerfect match! Intense hydration without heaviness. Layer for extra moisture or use as overnight mask.
5-layer HA complex deeply replenishes water levels. Clinically proven 48-hour hydration.
Lightweight formula hydrates without adding oiliness. Absorbs quickly with no residue.
Watery texture absorbs well. Best used at night. May prefer lighter formula in summer.
Fragrance-free, alcohol-free formula with soothing Panthenol and Licorice. Patch test recommended.
Low comedogenic rating (1/5). Niacinamide helps with blemishes. Caution if prone to fungal acne.
Results timeline
4+ WEEKSInstant Hydration Boost
Skin feels plump, refreshed, and hydrated right after application. Watery texture absorbs within seconds leaving a dewy, non-sticky finish.
95% noticed instant hydrationGlass Skin Glow
Wake up to visibly smoother, more radiant skin. The overnight mask effect leaves skin looking refreshed and luminous.
88% reported morning glowImproved Skin Texture
Consistent use reveals smoother skin texture. Dry patches and flakiness significantly reduced. Skin feels more elastic and bouncy.
82% saw texture improvementStrengthened Moisture Barrier
Long-term benefits include improved skin barrier function, reduced sensitivity, and more balanced hydration levels throughout the day.
75% reported barrier improvementRatings by platform
9K+ REVIEWSPros & cons
BALANCEDPraised
- Intense hydration without sticky or greasy feeling
- Lightweight, watery texture absorbs in seconds
- Visible "glass skin" glow by morning
- Fragrance-free and alcohol-free
- Great value - bottle lasts 2-3 months
- Works well under makeup
- Suitable for sensitive skin
- No ferments (unlike No.3 serum)
Criticized
- "Sleep mask" naming is misleading - it's a serum
- Too watery for those expecting thick mask
- May not be fungal acne safe for all
- Some users needed additional moisturizer
- Rare breakouts reported by sensitive users
- Pump can be imprecise
Budget-friendly alternatives (dupes)
DUPESSimpler formula with 2% HA and panthenol. Fewer molecular weights of HA and no glacier water, but similar hydrating effect at a fraction of the price.
Contains 3% HA with ceramides and NMF complex. Comparable hydration but different botanical blend. Also Korean skincare.
Different approach using 96% snail mucin instead of HA. More soothing and regenerative, slightly thicker texture. Great for damaged skin.
Similar HA-focused formula but with added peptides and green tea enzyme. More luxurious feel but less value for money.
Comparison with competitors
SIDE-BY-SIDEStorage & shelf life
12 MONTHS12 months after opening
Store in cool, dry place away from direct sunlight. Refrigeration optional but can enhance cooling effect.
Pump bottle with secure cap. Hygienic dispensing prevents contamination.
Yes, under 100ml TSA limit. Compact pump bottle fits easily in toiletry bag.
Frequently asked questions
FAQYes! This serum is considered safe during pregnancy and breastfeeding. It contains no retinoids, salicylic acid, hydroquinone, or chemical sunscreens. All ingredients including niacinamide, hyaluronic acid, and botanical extracts are generally recognized as safe during pregnancy. However, always consult your healthcare provider if you have concerns.
Use with caution. While this serum is free of ferments and most FA triggers, it contains Polyglyceryl-10 Laurate which may not be fungal acne safe for everyone. Many users with FA-prone skin report no issues, but if you're highly sensitive to FA triggers, patch test first or consider an alternative. Note: This formula is much safer than the No.3 serum which contains galactomyces ferment.
Yes! This hydrating serum pairs well with most actives. It's especially beneficial alongside retinol as it helps combat dryness and irritation. For vitamin C, apply the serum after to lock in moisture. With AHA/BHA, use the serum to soothe and hydrate post-exfoliation. The niacinamide in this formula works synergistically with most actives.
This serum is excellent for dry, dehydrated, combination, and sensitive skin types. It's particularly beneficial for anyone seeking intense hydration without heaviness. Oily skin types can use it but may prefer nighttime only. It's ideal for those wanting the "glass skin" effect and works well for dull, lackluster complexions needing a radiance boost.
Immediate: Instant hydration and plumping effect. Next morning: Visible glow and smoother skin texture. 1-2 weeks: Improved overall skin texture, reduced flakiness. 4+ weeks: Strengthened moisture barrier and more balanced hydration. Clinical tests show hydration up to 2.5mm deep with 48-hour moisture retention.
Apply after cleansing and toner/essence, before moisturizer. In the PM routine, it can be used as the last step for an overnight mask effect. Order: Cleanser → Toner → Essence → THIS SERUM → Moisturizer → SPF (AM). For intense hydration, apply two thin layers. Works best on slightly damp skin to enhance absorption.
No, this serum has a very low comedogenic rating of 1/5. Most ingredients have a 0 comedogenicity rating (glycerin, hyaluronic acid, panthenol). The watery, lightweight texture absorbs quickly without leaving residue. It's silicone-free and oil-free, making it suitable for acne-prone skin. However, individual reactions can vary, so patch testing is always recommended.
The serum has a 12-month PAO (Period After Opening). Store in a cool, dry place away from direct sunlight. The pump bottle helps prevent contamination. Most users find the 50ml bottle lasts 2-3 months with daily use (2-3 pumps per application). If you notice any change in color, texture, or smell, discontinue use.
Verdict: The Numbuzin No.6 Deep Sleep Mask Serum delivers on its promise of intense, long-lasting hydration in a lightweight, fast-absorbing formula. The 63% Iceland Glacier Water base combined with 5 types of hyaluronic acid creates a powerful hydration cocktail that rivals products at twice the price. While the "sleep mask" naming is somewhat misleading (it's really a hydrating serum), the results speak for themselves - plump, dewy, glass-skin glow by morning. Perfect for dry, dehydrated, and combination skin types seeking K-beauty hydration without stickiness or fragrance. A few points off for the potential fungal acne concern and marketing gimmick, but overall an excellent value that lives up to the Numbuzin hype.
Product Overview
Quick product notes are a great way to check if a product is free from commonly avoided ingredients by skincare enthusiasts. These preferences come about for different reasons depending on the ingredient such as personal experiences, sensitivities, health preferences & etc.
Just because a product is not free from a common preference does not mean it's a bad product! You can make a personal decision whether or not you want to use a product that contains these ingredients or not - click the labels of the preference to read more about them.
Quick Product Notes
Ever used a product that promised a certain effect but provided no results? It might not have contained any notable ingredients that could have been responsible for that promised effect. It doesn't matter what the marketing or packaging «promises» it can do, if it doesn't contain anything that can help - then the likelihood of it helping is low.
We help you identify key notable ingredients that have been shown to help with effects such as acne-fighting, brightening, UV-protection, wound healing & anti-aging to help you achieve your skincare goals smarter. Please note that different notable ingredients have varying levels of research behind them, some are extremely well proven yet some have mixed research in their efficacy.
Just because a product doesn't contain any notable ingredients doesn't mean it's bad. And a product with notable ingredients (or even many) doesn't necessarily guarantee the efficacy of the product performing these effects either. There are other factors such as ingredient quality, concentration and formulation that will ultimately determine this.
Be smart and use this as just a starting point for you to make more informed and smarter choices and compare it with reviews to see if the product is right for you
Notable Effects & Ingredients
Why are some products great for some people and horrible for others? Well everyone has different skin types and different reactions to the same ingredients.
We've identified a range of ingredients that are commonly regarded as potentially good or bad for those with Dry, Oily/Acne-Prone or Sensitive skin.
A product that contains good or bad ingredients for your skin type doesn't always flat out make the entire product good or bad for your skin. There are other factors such as ingredient quality, concentration and formulation that will ultimately determine your skins reaction.
One of the best ways to use this section is to troubleshoot products you've had bad experiences with in the past. Check if it contains any of the marked ingredients to point out suspect ingredients to avoid in the future!
Ingredients Related to Skin Types
Ingredient Safety Breakdown refers to the percentage % of ingredients in different risk categories as classified by EWG (Environment Working Group) if they are available. There are almost endless cosmetic ingredients and they are one of the few organisations globally that have assigned ratings to a lot of the more commonly used ingredients which is why we reference them.
EWG is seen by many to be more on the alarmist side in their assignment of health ratings resulting in rating ingredients as riskier than they actually are. We recommend using this a reference point rather than a strict guide of ingredient safety and to always do further research if into ingredients that you may find suspect.
Ingredient Safety Breakdown
Product ingredient list
| EWG | CIR | Ingredient Name & Cosmetic Functions | Notes |
|---|---|---|---|
| 1 |
Water
Solvent, Skin Conditioning
|
|
|
| 1 |
Butylene Glycol
Solvent, Skin Conditioning, Masking, Fragrance, Humectant, Viscosity Controlling, Viscositydecreasing Agent
|
Hydrating
|
|
| 1 |
Propanediol
Solvent, Viscosity Controlling, Viscosity Decreasing Agent
|
|
|
| 2 |
Glycerin
Solvent, Perfuming, Fragrance, Humectant, Viscosity Decreasing Agent, Hair Conditioning, Skin Protecting, Denaturant, Skin Conditioning
|
Promotes Wound Healing
Hydrating
|
|
| 1 |
Niacinamide
Skin Conditioning, Hair Conditioning, Smoothing
|
Promotes Wound Healing
Redness
Irritation
Dark Spots
Pores
|







