Skin cycling — alternating exfoliation, retinoid, and recovery nights in a 4-night rotation — became a TikTok trend in 2022. The format is actually how most dermatologists have been advising patients for decades; the popularisation just gave it a name.
The 4-night rotation
Night 1: exfoliation (AHA or BHA leave-on serum). Night 2: retinoid (retinol or stronger). Night 3: recovery (moisturiser only, focus on barrier repair). Night 4: recovery (moisturiser only). Then repeat.
Why it works better than daily everything
Spaces out irritation, allowing barrier recovery between active nights. Reduces over-exfoliation risk significantly. Most users tolerate this format who couldn't tolerate daily acids + daily retinol.
If your current routine includes daily acid and daily retinoid and you're seeing sensitivity, skin cycling is the format that solves it without abandoning the actives.