A woman with a swatch of nighttime retinol skincare

Why You Should Only Use Retinoids at Night

There’s a lot of online chatter surrounding when to use retinoids: most dermatologists say nighttime is best, but some say that's just a myth. We asked board certified dermatologist Dr. Sandra Lee (aka Dr. Pimple Popper), who says it’s best to use retinoids (including retinol) at nighttime — here’s why.


3 minute read

There’s a lot of online chatter surrounding retinoids: who should use these potent vitamin A derivatives, what forms are best, and when should you apply them? Complicating the conversation are a set of common misconceptions that can be confusing.

Today we’re examining the when question with Dr. Sandra Lee (aka Dr. Pimple Popper). Put simply, she says it’s best to use retinoids (no matter which form) at nighttime — here’s why.


What happens to your skin at night?

We’ve talked about circadian rhythms before: commonly known as your biological clock, these chemical and electrical signals regulate all of the processes in your body — including your skin. At nighttime, these signals tell your skin to repair and regenerate itself, leading to a cascade of events including:

  • Increase in skin barrier permeability
  • Skin cell proliferation
  • UV damage repair
  • Wound healing acceleration

What retinol does to your skin

Let’s brush up on our retinol basics. This potent antioxidant, when applied topically, undergoes two chemical reactions (becoming retinoic acid) before binding to special receptors on the skin cells called RARs. Once they’re locked in, these retinoic acid molecules tell your skin cells to divide faster.

You may remember that this initiates what’s called the skin cycle: when new cells are created and continually pushed to the surface by even newer cells beneath. These skin cells change in shape and function as they get closer to the surface, and eventually slough off (called desquamation).

So retinol increases the skin cycle, which means that your skin is newer and fresher when you’re using it, and shedding those older, tougher cells on the surface more often.

Why it’s better to use retinol at night

Now that we have a better understanding of exactly how retinol works, it makes sense that applying it at night is ideal. There are several reasons why Dr. Lee suggests that patients limit their use of retinoids to evening only:

  • To coincide with your natural skin cycle. Since cell division peaks at night — that circadian rhythm we mentioned earlier — applying retinol at night supports your cells efficiently.
  • So it doesn’t conflict with other active ingredients. Using retinol at the same time as highly concentrated AHAs, vitamin C, and benzoyl peroxide can cause a loss of efficacy, as well as irritation in some people.
  • Because it breaks down in sunlight. Studies indicate that UV exposure chemically alters the composition of retinoids, making them less effective.

Can you use retinol during the day?

One of the most hotly debated topics online is whether or not retinol makes your skin more sun sensitive. There is conflicting evidence on the subject:

  • The “avoid sun” school of thought says that because retinoids reduce the thickness of the stratum corneum (that’s the outermost layer of dead skin cells), your newer, more delicate skin beneath is more vulnerable to UV rays.
  • The “sun is fine” proponents surmise that most of the perceived “sun sensitivity” may in fact be due to the initial irritation that’s typical of the first several weeks of retinol use — as evidenced by observations that the skin often seems to “adjust” and show more typical sunburn propensity over time.

Dr. Lee has a practical take on the controversy. “We all know that UV rays cause inflammation, and damage skin,” she says. “Using an active ingredient like retinol that’s working to minimize acne, or premature aging, or both, seems counterintuitive during the day, when your skin is in ‘protect’ mode rather than ‘repair’ mode.’” Essentially, whether or not you can use retinol during the day is less important than whether or not it really makes sense to do so.

What is the best nighttime retinol product?

There are countless over-the-counter retinol formulas on store shelves, along with quite a few prescription retinoid options available. Choosing one with high-quality ingredients formulated to suit your skin type and goals is the key to achieving noticeable results.

According to Dr. Lee, OTC retinol is suitably effective in most people for addressing both acne and anti-aging goals. SLMD Retinol Resurfacing Serum features a time-released formula that also contains hyaluronic acid to work gently overnight, as part of an anti-aging or acne-fighting regimen.

Dr Sandra Lee

Dr. Lee's Last Word

Studies have begun demonstrating what we dermatologists have long suspected: retinoids just work better overnight. Retinol is one of my favorite ingredients, because it’s been proven effective at treating acne and minimizing extrinsic aging in study after study. It’s the best advice I can give to people: wear sunscreen during the day, and use retinoids at night.


Shop the Article