We’ve all heard that night creams work better because your skin absorbs ingredients while you sleep. Is this true? Tune into to this week’s show to find out. Also, Randy and I talk about how beauty companies cut costs on cosmetic formulas.
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Question of the week: Do night creams work better at night?
Christine says…I’ve read that night creams are supposed to work better because the skin heats up at night so the ingredients penetrate more deeply. Is this true?
What happens to your skin at night?
First of all, there doesn’t seem to be any question that sleep is good for skin. Lack of sleep can actually impair the barrier function of skin which means TEWL is increased. In other words – not getting enough sleep literally dries out your skin. For example, one study found that “Sleep deprivation also decreased skin barrier function recovery and increased plasma interleukin-1beta, tumor necrosis factor-alpha, and natural killer cell activity.” So dryness, psoriasis, eczema, and other types of dermatitis can be triggered by lack of sleep.
The hypothesis which explains this is that sleep gives the body time to repair itself. During the day the sympathetic nervous system is in control and it keeps blood flow near the core of the body. At night the parasympathetic system takes over and it shifts blood flow to the extremities. Theoretically, this is when the skin builds more collagen. In addition, the kidneys are more active during the parasympathetic phase and they are able to drain excess fluid that can create puffy eyes. So, sleep is good for skin but does it actually cause the skin to “heat up” as Christine mentioned?
Ref: Stress-induced changes in skin barrier function in healthy women. J Invest Dermatol. 2001 Aug;117(2):309-17. http://www.ncbi.nlm.nih.gov/pubmed/11511309
Does the skin heat up at night?
The answer is yes, at least for part of the night. We found a study which measured blood flow and skin temperature during sleep. By the way the technical term for this is nocturnal subcutaneous blood flow. The researchers found that after about an hour of sleep blood flow does increase to the skin (at least to the legs which is what they measured in the study.)
They also found that with this increasing blood flow comes a statistically significant increase in temperature which makes sense since the body cools itself by vasodilation. Interestingly this effect lasts for about two hours before returning to normal levels. So if you’re not sleeping for at least three hours total it doesn’t seem to make much difference.
This all means that Christine is correct – it does appear that as you sleep subcutaneous blood flow and skin temperature both increase. But, what impact does this have on the absorption of cosmetic ingredients through your skin?
Do increased temperature and blood flow lead to increased ingredient absorption?
There are two parts to this answer: first there’s the question of how well ingredients diffuse through the outer layers of skin to get to the bloodstream. Second there’s the question of how well the ingredients are absorbed into the blood stream once they pass through the skin.
As far as we can tell, no one has done a study correlating blood flow and the absorption of cosmetic ingredients. However, there’s plenty of research on the factors that affect absorption of drugs that are applied topically to the skin. For example, one study found that physical exercise increased plasma concentrations of nicotine during treatment with a nicotine patch. The researchers attributed this increase in absorption to “an exercise-induced increase in blood flow in the patch area.” http://www.ncbi.nlm.nih.gov/pubmed/7654487
So, yes, blood flow can increase absorption at least of drug ingredients that are designed specifically to penetrate all the way through skin. We could find no evidence that it would increase penetration of ingredients that are NOT prone to penetrate in the first place.
What about heat? Does that increase absorption? One study measured the effect of applying heat at the site of subcutaneously injected insulin. Since it was injected it bypassed the outer layers of skin. The results showed that increasing skin temperature did NOT cause the insulin to perfuse through the remaining tissue to any greater extent. And, considering that this was externally applied heat which was greater than what you’d experience from a modest increase in blood flow, it seems very unlikely that a small increase in skin temperature due to blood flow would impact ingredient penetration. http://www.ncbi.nlm.nih.gov/pubmed/22162782
Do night creams provide ANY special benefit?
We haven’t been able to find convincing evidence to indicate that night creams are better because your skin absorbs ingredients better as you sleep. But is there ANY benefit to applying products at night? Yes, there are a couple of reasons why you might want to use a night cream.
First, some cosmetic ingredients make skin more sensitive to sunlight which means you could experience increased irritation or photo damage if you’re wearing these ingredients while in the sun. If you wear a sunscreen this may not be an issue but you can also get around that problem by applying these ingredients at night. Here are some examples of ingredients that can make skin more sensitive to sunlight:
- AHAs – like lactic acid or glycolic acid.
- Benzoyl Peroxide – the antiacne agent.
- BHAs – or Beta Hydroxy Acids like salicylc acid.
- Hydroquinone – which is used for skin whitening
- Retinol – the popular anti-aging ingredient.
- Some natural ingredients – like citrus oils, peppermint oils, lavender, etc may increase photosensitivity.
Second, some ingredients are just too aesthetically unpleasant to wear during the day. For example, you wouldn’t want to walk around with a heavy, greasy moisturizer on your face but you might not mind sleeping with a moisturizing mask on.
Don’t just take our word for this
Finally, don’t just take our word for this. Paula Begoun, the Cosmetic Cop also says night creams are mostly BS. She says:
“The ONLY difference between a daytime and nighttime moisturizer is that the daytime version should offer sun protection.”
“…cosmetics salespeople say is that the skin needs different ingredients at night than during the day…If that’s the case there isn’t a shred of research or a list anywhere of what those ingredients should be. Skin is repairing itself and producing skin cells every nanosecond of the day, and night.”
“Regardless of the time of day, your skin needs all the current state-of-the-art ingredients it can get. Saving these ingredients only for nighttime use is cheating your skin of the benefits it could be gaining during daylight hours, too!”
The Beauty Brains bottom line
Yes there are some changes that occur within your skin at night and sleep is certainly beneficial to skin. However, that doesn’t mean that night creams provide any special functionality. In general it’s more about avoiding things that you wouldn’t use in the sun rather than adding things that work better at night.
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Does the skin heat up at night? It sure does! Ask any woman who has hot flashes and night sweats! LOL
Seriously, though, I’ve always considered the insistence on seperate day and night creams to be just so much marketing. True, I only use my prescription strength retinoic acid cream at night but that’s because of how sunlight interacts with it and has nothing to do with whether or not I’m sleeping. Perhaps because sleep is such a mystery to us on many levels, marketers find it fertile ground for their promises. Learn a new language while you sleep! Lose unwanted pounds while you sleep! Train your brain while you sleep! And, how about this one–Sleep while you sleep! 🙂 As always, great job guys.
Thanks Eileen. I just hope that our podcasts aren’t putting people to sleep!
I love your podcasts! They are pure gold. But I do use them to help me fall asleep so you’re helping me with my beauty in another way too! Don’t worry, it’s not because they are boring (on the contrary, they are funny and help me with my mood before sleep), I just need something to engage my overactive mind to be able to stop thinking of a million things and relax instead. So I need something interesting to listen to in order to fall asleep, it should also be light-hearted and positive (I used to go with my favorite TV show but got tired of it and meditation audios are not nearly as effective). So you’re helping me with my insomnia that I’ve had my entire life and I thank you for that. I know it’s a very unexpected effect for you but I think it’s pretty cool so take it as a compliment because it is. I love your blog!
Thanks, Tree! Sweet dreams!
Not all menopausal women experience hot flashes.
Interesting topic, thank you so much for explaining! I always wondered whether there is more difference than UV protection, since night creams are typically thicker.
My reason for using different day and night creams is that not every cream works well with make up. In the morning, I only apply a light serum to dry areas of my skin under my foundation. At night I can use a richer texture since I won’t apply anything else.
Excellent point, Lizzy. We didn’t think of that one.
Thanks, I used to think about the different between day and night cream was the uv filter ingredient. By now i know much more about them.
Ps: I like your websites so much
thank you for further clearing up the night cream enigma…i always enjoy reading your blog
cosmetic companies will always try you to sell the idea (and their night cream) that at night time skin proliferation and regeneration peaks. that’s why it would make sense to have a night cream whose ingredients would cater to these phase of proliferation and regeneration. however, while it would somehow make sense that skin regenerates (and proliferates) more during night than daytime, the scientific back up data does not seem to be unequivocal, as data from mouse skin can not extrapolated to human skin. recent research (Janich et al. Stem Cell 2013) indicates that keratinocytes and fibroblasts have an inner clock when it comes to gene expression. external factors (like UV) might trigger these inner clock gene expression, so also human (not only mouse) skin cells can somehow anticipate when it is time to regenerate and handle delicate DNA replication (which would be during night), and when it is time to protect itself (e.g. from UV during daytime). So there might be a reason to apply certain different ingredients at night and at day sometime in the future, when there is more data on this clock gene expression in human skin cells and we would know what would be the best way to support our skin cells during these different processes day and night. in the meantime i totally agree with our beauty brains, the reason for investing into a night cream and a day cream would be that you rather use the heavy, probably oil-in-water moisturizer with light sensitive ingredients at night, while the spf containing, fast absorbing lighter moisturizer is applied during daytime.
i don’t know if a higher skin blood flow would be a good thing for absorption of skin ingredients, higher blood flow could also mean faster removal of the ingredient from the skin.
That’s a very thoughtful analysis, Grex. Thank you!
Thank you for your podcast. I just wanted to mention that the protocol for Dr. Hauschka is to skip the night cream:
¨According to Dr. Hauschka, using night creams means keeping the skin moisturized for 24 hours. That may seem like a good thing at first, but it actually interferes with the skin’s regeneration and its essential functions of balancing oil production and expelling impurities. Keeping the skin moisturized round the clock “sends a signal to sebaceous glands to cut down on moisture production, resulting in even drier skin that becomes dependent on moisturizing products just to appear ‘normal’.”
The team at Dr. Hauschka recommends using their Rhythmic Night Conditioner instead of more traditional night creams, since it supports the skin’s regenerative processes during the night, and helps balance oil production.¨
What do you think of this approach?
We’ve talked about this approach to sebum regulation before: https://thebeautybrains.com/2014/08/25/why-does-your-skin-get-so-oily/
It’s a surprisingly controversial subject!
I love your podcasts! You are both very smart, funny and have a great synergy that entertains me while I’m listening…you guys actually make me giggle out loud. There has only been 2 podcast series that I have downloaded every episode and listened to every one of them, and your podcast is one of them. I have a long commute to work and I have been listening to you guys every day for over a month now.
My friend and I have become partners to develop our own skincare line. She owns a honey shop, which sells delicious food. 🙂 I have a natural health website and create tinctures, oil concoctions, etc. We have developed body scrubs, masks, soaps, etc… trying to incorporate honey in the products.
Skin lotions on the other hand aren’t as easy to develop. I guess that is why people go to school for chemistry 🙂
I’ve been experimenting with different ingredients trying to develop a mature skin night creams. I just find them too heavy and oily and I was wondering if you have any opinion on the best base ingredients for a night cream or maybe a link to information about it? Some items I’ve tried are shea butter, body butter, coconut oil, palm oil, in addition to other oils and essential oils. I just don’t want the product to cause acne or clog pores.
I am a software engineer, but I love natural health and I started a natural health website on the side, because I enjoy helping people. Listening to you guys have changed my opinion on some of my natural views on products. I still believe we should minimize our exposure to chemicals as much as we can, but I now have a better appreciation of the purpose of some ingredients in topical products. I’m so happy I found your podcast! I’ve been learning so much from you. Keep up the good work.
I’m trying to be educated, have an open mind and be ‘Brainy about my Beauty’