There are moisturizers for daytime and nighttime use:
Day creams tend to be a bit lighter and usually contain sunscreen. It protect our skin from UV rays, and provide a protective layer between our skin and make-up.
Night creams tend to be a bit heavier and contain ingredients like collagen, vitamins and anti-aging components. The cell renewal of our skin is more active at night, using a night cream gives our skin the chance to repair the damage caused by make-up, pollution and UV rays.
If a moisturizer is designed for both day and night use, then always remember to apply sunscreen in the morning.