The Science of Circadian Skincare:

For decades, skincare has largely focused on ingredients. Stronger actives, higher percentages and increasingly complex routines have shaped how we approach our skin.

But a growing area of research is shifting that conversation toward something else: timing.

The skin follows a circadian rhythm, a 24-hour biological cycle that influences how it protects, repairs and regenerates itself. Throughout the day and night, processes such as barrier function, antioxidant activity and cellular renewal fluctuate.

This concept sits at the heart of Raeso, the New Zealand skincare. Rather than layering products without regard for timing, Raeso formulates with the skin’s natural rhythm in mind.

To better understand the science behind this approach, we spoke with Raeso founder Katey Mandy about circadian biology, the influence of New Zealand’s landscape and why timing may be one of the most overlooked elements in skincare today.

In Conversation With Katey Mandy, Founder of Raeso

1. What first sparked your interest in circadian biology and how did that lead to the creation of RAESO?

I’ve always been fascinated by the intelligence of the skin. Chronobiology is the science that every cell in the body operates on a 24-hour rhythm. Skin is no different.

During the day, it operates in defense mode and works to protect itself from UV, pollution and environmental stress. At night, it shifts into repair mode, rebuilding DNA, regenerating cells and restoring the barrier.

Over the past decade, science has been uncovering more and more about how profoundly the skin operates on a 24-hour biological rhythm. Almost every key skin function - barrier strength, antioxidant defense, DNA repair, cell turnover and even ingredient permeability - fluctuates across the diurnal cycle.

It really surprised me when I realized that most skincare ignored this completely. We were layering dozens of ingredients, without consideration for when the skin could actually use them best.

RAESO was born from that insight. Instead of forcing skin to behave differently, we formulate in alignment with its natural rhythm, delivering antioxidants when defense peaks and renewal ingredients when repair accelerates. When skincare works with biology rather than against it, results can be faster and skin becomes stronger over time.

2. Skin behaves differently throughout the day and night. What are the most important shifts people should understand when thinking about their skincare routine?

The biggest shift is that skin has two very different jobs depending on the time of day. Think of it almost as two different skins.

During daylight hours, the barrier is at its strongest and the skin is focused on protection. This is when antioxidants and SPF are at their most important, working together to defend against UV, pollution and oxidative stress.

At night the skin becomes more permeable and repair-focused. DNA repair accelerates, cell turnover increases and ingredients can penetrate more effectively. This is when renewal ingredients like retinal or barrier-supporting actives perform best.

When people understand that shift, routines become much simpler. You don’t need ten products. You just need the right ingredients at the right time. Less is more when you meet the skin where it’s at.

3. RAESO draws inspiration from New Zealand’s unique environment. How has the landscape and its botanicals influenced the formulas you create?

Growing up in New Zealand had a huge influence on how I think about skincare. I spent a lot of my childhood helping my father re-wild our family farm with native plants, and it ingrained in me a deep respect for the intelligence of those ecosystems.

New Zealand botanicals have evolved under incredibly intense environmental conditions, some of the highest UV levels in the world, dramatic temperature shifts and very clean but exposed landscapes. Because of that, many of these plants developed powerful protective compounds.

We incorporate ingredients like mānuka, sauvignon blanc grape seed, kānuka, alpine rosehip and marine algae because they are naturally resilient. In many ways they mirror exactly what skin needs: protection, repair and adaptation.

RAESO sits at the intersection of nature and chronobiology. Our formulas combine botanicals that evolved in extreme environments, with delivery systems designed to work in sync with the skin’s biological clock.

4. Many people focus on ingredients, but your approach also considers timing. How do you see the future of circadian skincare evolving?

Timing is the missing layer in skincare science. For decades, the industry has focused on stronger ingredients or higher percentages. The next frontier is precision: delivering the right ingredients when the skin is biologically primed to use them.

We’re already seeing breakthroughs in encapsulation technology, controlled-release delivery systems and bio-adaptive ingredients that respond to environmental stress. These technologies allow ingredients to work long beyond the moment of application.

The future of circadian skincare will combine biology, technology and timing. Think formulas that release actives gradually through the day, or at night when they can best support the skin’s natural repair cycles.

5. When someone is new to circadian skincare, what is the simplest way to begin aligning their routine with the skin’s natural rhythm?

Start with just two moments in the day.

In the morning, focus on protection. Cleanse, apply your antioxidants, and always finish with SPF. Support your skin in doing its job of defense during the day.

Shift your support to repair in the evening. After cleansing, use renewal ingredients like a retinal serum, and a ceramide barrier cream to help the skin rebuild overnight.

You don’t need a complicated routine. The goal isn’t layering more products. It’s simply working with what your skin is already trying to do. Once people understand that rhythm, skincare becomes much more intuitive.

Discover Raeso at Ara'kai

Raeso’s perspective on skincare reflects a thoughtful balance of biology, environment and cosmetic science. The formulas combine circadian research, resilient New Zealand botanicals and advanced cosmetic formulation. This approach is further informed by the work of molecular biologist Dr. Dan Yarosh, a pioneer in DNA repair science and former scientific advisor to Estée Lauder and La Mer.

We are pleased to welcome Raeso to Ara’kai’s assortment and to introduce the brand exclusively in Denmark. The collection includes formulas such as the Morning Dew Vitamin C Serum, Sun Milk Drops SPF 50, Yellow Moonbeam Retinal Elixir and Cocoon Ceramide Cream. Each is designed to support the skin at different moments across the day and night.

You can now discover the Raeso collection at Ara’kai in store and online.