Your skin, a complex organ that functions like a body clock with a circadian rhythm which affects dermal functions, is smarter than you might think, and its needs differ depending on the time of day.
Circadian rhythms are a 24-hour cycle of physical and behavioral changes which are affected by the light and darkness in a person's – or indeed any organism's – environment. Also known as the body clock, circadian rhythms dip and peak at different times of the day, dictating our sleepiness and wakefulness - most people's strongest sleep drive occurs between the hours of 2am and 4am, when there is very little exposure to natural light, for example. But recent research has uncovered a similar mechanism in skin cells, which controls skin health and anticipates when the skin will be under the most stress, therefore when repair is most needed. It is thought that circadian variations affect all skin functions, from cell renewal and hydration to sebum secretion.
The main concern with skin during the daytime is protection. At this time, skin is coming up against environmental aggressors including UV light and pollution, which is why antioxidant products are needed here. 'The majority of antioxidant support should be applied in the morning, Antioxidants are designed to decrease free radical damage, which is at its height during the day when our skin is exposed to these environmental aggressors and UV radiation.
Sebum production peaks in the afternoon and is why no matter how matte your complexion upon arrival at work, a little lunchtime shininess is normally the case. People experience oiliness in the afternoon for multiple reasons, stress could trigger the oil glands in the skin, but dry skin can also be a culprit as skin will attempt to hydrate itself by overstimulating the oil glands. As well as ensuring you are using a good moisturizer, be sure to drink as much water as possible during the day.
Your evening skincare arsenal should be separate to your daytime one for multiple reasons. 'Many ingredients, specifically Vitamin A products (retinoids) are considered sun sensitive and should not be applied when the skin is exposed to UV radiation. The nighttime is also the time during which the skin's repair mechanism kicks in. Stem cells in the epidermis reproduce largely at night and are responsible for creating new skin cells.
Nighttime dryness is thanks in part to trans-epidermal water loss which occurs over the course of the day. If you suffer from certain skin conditions, you might notice this flare up at this time. Conditions such as psoriasis and eczema have a marked absence of aquaporin channels [the channels which control the passage of water molecules in and out of a cell). Assisting in preventing trans-epidermal water loss by rehydrating these channels with an adequate hydrating cream can help reduce the symptoms associated with these skin conditions.'
The Study of Circadian Rhythms in the Skin
'The importance of circadian rhythms, which started in the 1700s with a French scientist Jean-Jacques d'Ortous de Mairan, has led to the development of a new science associated with the effects of time on the body, called chronobiology.
While our body clocks have been set in a certain way over thousands of years, a relatively new phenomena is putting them out of sync. The blue HEV light found in phone and computer screens has been found to disrupt or reset our circadian rhythms. 'It also slows the production of melatonin that signals to our brains that it's time for bed. Some smartphones now have a 'night shift' mode which sets the light given off by your device to a more orangey hue, less similar to the daylight-replicating blue light we ordinarily have our phones set to.
Equally, simply putting your phone down and going to bed with nothing more sophisticated than a book will have the same effect. Think of it as doing it for your skin's sake.