Essence can be used at night or in the daytime, but the specific use time and effect will vary depending on the type and composition of essence.
Most of the essence can be used during the day or at night. However, some specific types of essence, such as essence containing Retinol and Hydroquinone, are easy to cause photosensitivity, so it is recommended to use them at night to avoid skin redness or even pigmentation. In addition, as VC essence is easy to be oxidized by air, especially essence that will accelerate oxidation under ultraviolet radiation is also recommended to be used at night to ensure its maximum effectiveness.
On the other hand, some essence contain special "ultraviolet absorber" and other ingredients with sunscreen effect. This kind of essence is suitable for use in the morning and can provide daytime protection for the skin. There are also some moisturizing essence, which are also suitable for use in the daytime if the texture is relatively fresh, especially when there is a need for makeup, it can help maintain makeup.
In general, the choice of when to use essence should be based on its ingredients and efficacy, as well as personal skin texture and needs.