After initially brushing off these off as just another fad, an attempt to form a new category out of what is really just a range of super-rich night creams I jumped in and bought one and immediately realised what all the fuss was about...

Comparing typical features and benefits.

Sleep Masks - Innovation from South Korea, the home of skin wellness!

Cosmetic chemists around the globe have had their research and development antennae tuned to South Korea for much of the last ten years. The country has earned a reputation of being the go-to place for scientific innovation in the high-value skin care space, especially in market segments such as sunscreen, cleansing formulation development and, arguably most famously, face mask technology. Sleep masks are part of the K-Beauty revolution, a sub-set of the 'mask' category that offers the efficacy and intensity of a mask-based treatment with the wearability and durability of a leave-on cream. The silky, barely-there textures for which K-Beauty has become synonymous define the Sleep Mask experience, making them quite a different tactile experience to your average night-based treatment product.

As for why South Korea is such a leader in skin care innovation, apparently that's what you get when you combine the cultural norm of caring for the skin as part of one's overall wellness - the Korean bathhouse or Jjimjilbang phenomenon - with the very modern habit of taking selfies (1)...

Meshing sleep science with beauty.

Most of us are familiar with the notion of beauty sleep and can relate to feeling brighter, fresher and more beautiful when fully rested but do we really give sleep enough consideration for the role it plays in keeping our skin looking its best or do we just take it for granted and hope for the best?

According to statistics, the average Australian gets 7 hours of sleep a night (2). While that doesn't sound too bad, when you dig further into the figures, a staggering 12% of Australians sleep less than 5 and a half hours per night and somewhere in the region of 33-45% of Australian adults are actually sleep deprived.

While we may feel like sleep is a passive activity, it is actually a very active process of rejuvenation which involves both mind and body (3). The skin responds to our circadian rhythms which operate on a 24-hour clock regulated by levels of daylight. Among other things, these rhythms affect and influence skin temperature, hormone production, histamine levels and even our natural anti-inflammatory system. One study found that reducing sleep by 25-50% outside of the optimal 8-hours per night led to elevated levels of inflammatory cytokines which could then go on to cause visible skin changes. In addition, sleep-depravation based alterations in histamine levels have long been linked to itching disorders and unexplained rashes which, in turn can make it harder to achieve a good night sleep. When it comes to the link between sleep and skin health, the information above is only the tip of the iceberg but even so, it's clear that the benefits of a good night's sleep are far from cosmetic. However, as cosmetic chemists rather than general health practitioners or sleep specialists it's time we got back to the sleep mask to see what promises such a humble-looking product is making and evaluate if they really do stack up!

The key features of sleep masks.

• Maximise beauty sleep
• Rehydrate
• Detoxify (deep cleanse)

Sleep masks draw on aromatherapy for their first benefit, often selecting well-known and evidence-based essential oils and natural aromatics to set the scene for a restful and rejuvenating sleep. It is well known that our sense of smell can trigger signs of an emotional response from us be they positive or not (6). Some smells evoke happy memories that may linger long after our perception of the scent has gone while others leave us feeling somewhat less than impressed. In some cases, these emotional responses can be measured physically (5). With sleep masks, the emphasis is on choosing scents that leave us feeling clam, relaxed and ready for sleep.

The aroma of Lavender is a popular choice and a number of studies have linked it with having a positive effect on sleep quality for those with mild sleep disturbances whilst presenting no negative side effects (5). Lavender is not just useful for its scent though, Linalool, a key aroma chemical found naturally in the oil, has also been extensively studied for its analgesic or pain-relieving properties. It is thought that this particular aroma-chemical is key to Lavenders anti-inflammatory efficacy, an action that is of particular importance in skin health and rejuvenation, especially of the type undergone at night (5).

Another popular choice for sleep masks is the citrus oils family which includes Sweet Orange and Bergamot. These oils have been found to reduce the stress responses in patients when inhaled. One particular study recorded a reduction in the physical markers of stress on the heart when Orange oil was inhaled although it failed to record a corresponding drop in psychological stress markers. This indicates that in that case at least, the body was responding more positively and strongly to the citrus chemistry than the mind (4). A further study found that rats who inhaled Bergamot oil prior to completing a cognitively challenging behavioural task such as navigating through a maze were less anxious than the control group. The reduction in anxiety in the Bergamot group was comparable to the rats treated with benzodiazepine diazepam (7).

Moving past the aroma we come to the next key feature of a sleep mask and that's its focus on moisture boosting. While night creams aim to lock in hydration, they often do so as function of their occlusivity rather than their inherent chemistry. What that means is a night cream creates a barrier-like second-skin of oil, wax and buttery ingredients that trap moisture underneath rather like a greenhouse. While night creams may contain ingredients such as hyaluronic acid, betaine and honey that hold large amounts of water, the cream base is designed to be generalists rather than specialists at moisture delivery.

Sleep masks focus almost entirely on pushing as much moisture into the epidermal layer as possible while using an osmosis-type action to pump other water-soluble actives deeper into the dermal tissue. Again, this is possible to some degree in a well-designed night cream but there will always be some moisture held back and therefore unavailable to the skin thanks to a night creams emulsion structure.

Sleep masks typically adopt a more serum-like chemistry, utilising oil-capturing or suspending thickener technology over an oil-in-water structured continuous phase (emulsion). Formulators carefully select high-tech three-dimensional thickening gels to achieve the right weight and texture for their target audience. These structure-forming gels are not just passive thickeners, many sleep masks include skin-active pre-biotic gellants such as crosslinked hyaluronic acids and biosaccharide gums which enhance skin rejuvenation in addition to the contribution they make to the products ultra-light, cooling and super hydrating aesthetics. This complex gel structure is typically designed with long-term hydration in mind and as such, a sleep mask should continue to hydrate your skin for the duration of your beauty sleep!

Sleep masks may capitalise on their emulsion-free status to build an active water phase. The water we secrete from our skin and that which bathes our skin cells is not just H2O, it's actually quite salty, often a little acidic and once we get to the dermal tissues, contains ceramides and free fatty acids. As such, sleep masks may deliver optimal levels of one more natural moisturising factor, thus creating either a biomimetic, or super-concentrated continuous phase that has the impact of making each drop of moisture more powerful and hydrating.

The last feature of a sleep mask is its detoxification powers and while the mechanism for this varies from brand to brand, the philosophy remains constant. Sleep time is the time when our minds and bodies undergo a deep cleanse and refresh. Typically, sleep masks come complete with antioxidant rich extracts, soothing agents, anti-inflammatories and vitamins, all designed to support the skins natural rejuvenation as you sleep.

New Directions Sleep Mask Solution.

Our Night Cocoon mask has been designed with long-term moisture delivery and skin comfort in mind. We have created a liquid-crystal, ultra-light melting-gel base and infused it with bio-compatible ceramides, super-hydrating hyaluronic acid and sleep enhancing lavender oil. This product features both fresh and encapsulated lavender technology CelluOil™ as a way of ensuring both the aromatherapy and physiological benefits of Lavender Oil are available to the skin throughout the night.

We recommend you apply the Night Cocoon after washing your face and applying your specialised skin serums. If you have skin that is oil depleted you may wish to apply a night cream over the top once the Night Cocoon has had a chance to sink in. Otherwise you can apply the night cocoon as your final step. In the morning the remaining product can be gently washed off to reveal a super-hydrated and rested complexion. Well, that's the hope anyway! This base can be customised by clients wishing to add their own finishing touches. Just remember, as with all customisations, do your stability and micro testing before committing to larger batches.

Amanda Foxon-Hill

Reference

1. Damjanovic, L., Wilkinson, H., & Lloyd, J. (2017). Sweet Emotion: The Role of Odor-induced Context in the Search Advantage for Happy Facial Expressions. Chemical Senses, 43(3), 139-150. doi: 10.1093/chemse/bjx081
2. Gupta, M., & Gupta, A. (2013). Sleep-wake disorders and dermatology. Clinics In Dermatology, 31(1), 118-126. doi: 10.1016/j.clindermatol.2011.11.016
3. How K-Beauty Took Over Global Skin Care. (2019). Retrieved 3 February 2020
4. Alleviation of the acute stress response following mild orange essential oil administration. IEEJ Transactions On Electrical And Electronic Engineering, 12, S158-S163. doi: 10.1002/tee.22428
5. Rombolà , L., Tridico, L., Scuteri, D., Sakurada, T., Sakurada, S., & Mizoguchi, H. et al. (2017). Bergamot Essential Oil Attenuates Anxiety-Like Behaviour in Rats. Molecules, 22(4), 614. doi: 10.3390/molecules22040614
6. Terlato, P. (2017). Australians aren't getting enough sleep - finder.com.au. Retrieved 3 February 2020