During sleep the epidermal (skin) stem cell produces cells that replace the aged ones. This generally occurs late at night or early in the morning, while we are resting and our bodies are not disturbed. It's one of the reasons our skin can appear more attractive in the morning.

Known as the lipid barrier, this is one of your body's first lines of defence against environmental aggressors and microorganisms. Your skin cycle changes throughout the day in order to protect and defend against various different elements – for example, in the morning your skin is more sensitive.

Throughout the day, the skin's water content fluctuates. Trans-epidermal water loss peaks overnight, and makes the skin more permeable to topical treatments. That is why this is the best time for applying skincare products and allowing them to work their magic.

Sebum is produced by your sebaceous glands to lubricate the skin and hair, making them waterproof. When too much builds up and sits on your skin, it can cause blocked pores and result in acne. Sebum excretion is at its highest around midday and lowest upon waking or late in the evening.

Whether you're a morning person or night owl is also down to your biological clock (circadian rhythm). It controls your sleep / wake-up cycles and is determined by specific genes, but also affected by age.