Our skin, the largest organ of the body not only changes with the seasons and environment but also exhibits fluctuations in physiology from day to night. These distinct shifts in biological activity are known as circadian rhythms. At night, our skin excretes less sebum, loses more water, is warmer, has a more acidic pH, and repairs itself more while we sleep than during the day. The skin’s metabolic rate increases and cells show increased production and a reduced breakdown of proteins, which is all good news for those who desire beautiful, healthy skin. While you are sleeping, your skin gets a reprieve from the trauma of the day and the body’s repair processes get a chance to catch-up. Exposure to UV rays contributes to photo-aging which includes degradation of our structural collagen along with a decline in hyaluronic acid resulting in wrinkles, fine lines and sagging skin. Dehydration is compounded by the fact that our lipid barrier layer diminishes with age and isn’t replenished as quickly. Certain prescription medications can increase dehydration and can also diminish the barrier function of the skin. In order to restore the integrity and health of the skin while sleeping, we need to address all of these issues with skin product selection. Blood flow seems to be higher at night and when blood flow is increased to the skin, the area of absorption of serums applied at night increases too. Products that contain water attracting humectants, skin softening emollients, lipid barrier reinforcements and collagen stimulating peptides restore and revitalize skin during the night time circadian rhythm.