The Kerastase 8H Magic Night Serum is designed to work while you sleep, promising softer, smoother, more hydrated hair by morning. Marketed as an overnight leave in treatment for dry and frizz prone hair, it claims to nourish for up to eight hours without leaving hair greasy or weighed down.
But does it actually deliver visible results, or is it just another luxury hair product with a beautiful bottle?
In this review, I tested the Kerastase Nutritive 8H Magic Night Serum on dry ends and slightly frizz prone hair to see whether it improves texture, reduces dryness, and makes styling easier the next day. Here’s exactly how it performs, who it’s best for, and whether it’s worth the investment.
But First, What It Is and How to Use It
The Kerastase 8H Magic Night Serum is an overnight leave in hair treatment designed to hydrate, smooth and nourish dry or frizz prone hair while you sleep. It sits within the Nutritive range, which targets dryness and dullness without weighing hair down.
Unlike traditional hair oils, this serum has a lightweight, creamy texture that absorbs quickly. It is designed to work over eight hours, gradually softening the hair fibre overnight.
How to use it:
- Apply to dry or towel dried hair before bed.
- Use one to two pumps for fine to medium hair, two to four for thicker or longer hair.
- Focus on mid lengths and ends.
- Leave in overnight, no rinsing required.
- Style as usual in the morning.
There is no residue on pillows, and it does not require washing out the next day unless you prefer to.
Our Review
As you can see in my before photo, my hair has been taking a real beating lately. Constant heat treatments mixed with its first bleaching in a while has left it damaged and it’s natural wave nearly non-existent.
I showered and then combed the Kerastase Serum through my hair, popped on a gel mask and a chick flick and had a perfect Friday night in. Overnight the Iris Root Extract and ‘5 Vitamin Blend’ worked their magic, and I was left with soft and bouncy waves the next morning.
Iris Root Extract is often used as an anti-aging ingredient in skincare as it helps to retain proteins, this makes a lot of sense for a hair mask as protein plays a big role in your hair strength. The 5 Vitamin Blend wasn’t revealed to me, and even after extensive googling I could only confirm 1/5 – Vitamin E which is used to reduce cell damage and encourage hair growth.
Since my first use of this a few weeks ago, I’ve been popping it on my hair once a week to keep it fresh and bouncy. If you’re looking for something to bring some spark and health back to your hair, then the Kerastase 8H Magic Night Serum truly is magic, and I would definitely recommend it!
Key Benefits You Can Expect
After consistent use, here is what you can realistically expect:
- Noticeably softer hair by morning
- Reduced surface frizz
- Easier detangling and styling
- Less dryness in mid lengths and ends
- A smoother finish without heaviness
It does not dramatically change texture overnight, but it improves manageability and hydration in a way that feels cumulative with regular use.
Pros and Cons
Pros
- Lightweight and non greasy
- Absorbs quickly
- Pleasant, subtle salon scent
- Helps reduce overnight dryness
- Works well on colour treated or heat damaged hair
- No need to rinse out
Cons
- Premium price point
- Results are subtle rather than dramatic
- May not be rich enough for extremely coarse or very damaged hair
- Scent may not suit everyone
It feels like a luxury maintenance product rather than an intensive repair mask.
Who It Suits Best
This serum is ideal for:
- Dry or dehydrated hair
- Frizz prone hair that needs smoothing
- Colour treated hair
- Fine to medium textures that dislike heavy oils
- Anyone who wants a low effort overnight treatment
It may not be sufficient for:
- Extremely bleached or heavily damaged hair
- Very coarse, thick textures needing deep repair
- People wanting dramatic overnight transformation
Think hydration and manageability, not structural repair.
Alternatives Worth Considering
If you are comparing options, here are alternative hair products depending on your needs:
For deeper repair:
Look at overnight hair masks or bond building treatments if your hair is heavily damaged.
For more shine:
A traditional hair oil may deliver stronger gloss, though it can feel heavier.
For budget friendly hydration:
There are pharmacy overnight leave in conditioners that offer similar moisture benefits at a lower price point, though often without the same lightweight feel.
For intense nourishment:
A weekly hair mask may be better suited if dryness is severe rather than mild to moderate.
Frequently Asked Questions
1. Does Kerastase 8H Magic Night Serum really work overnight?
Yes, it works as a lightweight overnight treatment that improves softness and manageability by morning. Results are subtle rather than dramatic, but hair typically feels smoother, less dry, and easier to style after one use, with cumulative benefits over time.
2. Is Kerastase 8H Magic Night Serum suitable for fine hair?
Yes. The formula is lightweight and non greasy, making it suitable for fine to medium hair types that are prone to dryness but dislike heavy oils. Start with one pump and focus on the ends to avoid weighing hair down.
3. Can you use Kerastase 8H Magic Night Serum on wet or dry hair?
It can be used on both towel dried and completely dry hair before bed. Applying to slightly damp hair can help distribute the product evenly, while using it on dry hair works well for targeting frizzy or dry ends.
4. Does it make hair greasy by morning?
No, when used in the correct amount. The serum absorbs overnight and does not leave a heavy or oily residue. Using too much product, however, may cause slight buildup, especially on fine hair.
5. Is Kerastase 8H Magic Night Serum good for frizzy hair?
Yes. It helps smooth surface frizz and reduces dryness, particularly on mid lengths and ends. It will not permanently change texture, but it improves manageability and softness with consistent use.
6. How often should you use an overnight hair serum?
For dry or frizz prone hair, two to three times per week is usually enough. It can also be used nightly if hair is particularly dehydrated, though adjusting frequency based on your hair type is recommended.
Our Verdict
The Kerastase 8H Magic Night Serum is a polished, well formulated overnight treatment that does exactly what it claims, gently improves softness, hydration and manageability while you sleep. It is not a miracle product, but it is a reliable one.
If your hair feels dry, frizz prone or slightly dull and you want a low effort upgrade to your routine, this is a strong addition. If you are looking for dramatic repair or transformation, you may need something more intensive. Overall, it is a luxury maintenance product that delivers consistent, subtle results rather than instant magic.
Want more beauty reviews? Click here for Alex’s review of IT Cosmetics Cult CC+ Cream.
Mmmm, I’ll give this a go my hair could do with some TLC
Would love to hear how you like it!
I’ll report back once I’ve bought some