The circadian rhythm is our 24 hour internal time-keeping system that regulates the cycles of alertness and sleepiness by responding to light changes. This is how our bodies optimize energy expenditure, the internal physiology and function of the body including hormone release. Interestingly, our skin has its own internal clock and is subject to a circadian rhythm as are all other organs. Studies have shown a correlation with ageing and circadian disruption as well as our bodies ability to respond to oxidative stress.
At night our skin is more active in cell regeneration and repair than during the early day. The bottom layer of the epidermis (the ones that create new cells) is most active late at night because it is not defending itself from environmental aggressors such as sun light and environmental pollutants. Also new cells are more susceptible to DNA photo damage during the day, so proliferation at night makes more sense. Skin repair is most active before the night. Skin wants to repair damage first before it proliferates.
There are two distinct sleep phases: REM (Rapid Eye Movement, when we have the most active dreams) and non REM sleep (deeper sleep) which are governed by the changes in light and dark. During Non-REM sleep, nightly cellular repaid and regeneration is enhanced in the skin. Not having restorative sleep not only leads to systemic inflammation but also increases the rate of age related processes.
What does sleep deprivation do to the skin?
Degradation of the circadian rhythm contributes to changes in hair growth, pigmentation and skin barrier function. Our bodies release the ‘sleep hormone’ melatonin which peaks around midnight. As we age, melatonin levels naturally diminish. Melatonin is also an antioxidant that helps protect skin from UV damage and counteract DNA damage. Without enough sleep, melatonin levels are impaired making skin less able to counter oxidative stressors.
Sebum production is also reduced during the restorative sleep phase and peaks in the early afternoon. Without the natural sleep pause, sebum production will stay elevated and can contribute to acne breakouts.
Sleep deprivation impairs insulin sensitivity in the body meaning that there are higher blood sugar levels, which in turn means there is increased production of AGE (Advanced Glycation End Products). AGEs work against the skin and accelerate is ageing process by increasing collagen degradation.
Telomere length is connected to sleep. Studies have shown that shorter telomere lengths are associated with poor sleep quality. Shortened telomer lengths means increased DNA damage of the skin leading to lacklustre, dehydrated skin.
Growth hormones, our body’s anti-aging hormones, are also affected by sleep. GH helps us look and feel younger and helps repair tissue and replenish collagen. Sleep allows for GH nightly peaks. When we do not have a good nights sleep, this GH level drops and is sub optimal.
We can not combat sleep deprivation completely but topical skincare ingredients stimulating collagen and elastin production can help. Collagen boosting actives like Vitamin A derivatives (prescription strength tretinoin), peptides, stems cells, and anti-oxidants are just a few of the ingredients that can be used to optimize healthy skin. The use of anti-oxidant skincare and SPF in the morning is essential to combat and prevent photo damage. In the evening, topical vitamin A helps to support the evening repair mode and helps improve overnight cell proliferation and skin regeneration. It is important to note that the skin barrier function is less effective at night, meaning there is increased water loss during this period. Richer skin care is used in the evening to help lock in hydration and moisture for this period. Together these support the skins natural circadian rhythm. But remember, getting your zzzz’s is equally as important!