Summer is over, the tan is fading, and what's left in the mirror is something no advertised serum mentions out loud: skin that looks more tired and slack than it did in June. Dermatologist Lidia Maroñas, founder of the Oneskin Med clinic, explains why - and why it is not just a matter of hydration.

The sun, she says, damages the skin on two fronts at once. First, it destroys existing collagen at the molecular level: the rays reach the dermis, trigger processes that break collagen and elastin fibres, and create free radicals that damage DNA. Second, they slow the synthesis of new collagen. In other words, the sun doesn't just tear things down - it also switches off the factory that is supposed to repair the damage.

One summer is not the same as twenty

Maroñas draws a distinction that is useful for anyone looking in the mirror right now. Damage accumulated over years of exposure permanently alters the skin's extracellular matrix and is hard to reverse. Damage from a single season, on the other hand, responds well to timely treatment - provided the treatment is aimed at restoring the skin's ability to produce collagen on its own.

The sun is not the only culprit. High blood sugar causes glycation, a process that makes collagen fibres stiffer and less elastic. Smoking reduces the oxygen reaching the skin. Alcohol brings dehydration and inflammation. Stress slows collagen production. And poor sleep shows on your face, because collagen synthesis happens mostly at night.

What clinics offer, layer by layer

For the most superficial layer, the epidermis, the dermatologist uses regenerative cosmetics: retinols, peptides, growth factors and exosomes, which send biological signals telling cells to renew faster. For the upper dermis - lasers that create controlled, precise micro-injuries to kick-start collagen and elastin production again. For deep damage - Endolift technology and micro-focused ultrasound, plus biostimulation with so-called skinbooster and skinbuilder treatments using amino acids, low cross-linked hyaluronic acid or diluted calcium hydroxyapatite fillers.

The list sounds impressive, and it is worth saying where it comes from: someone who runs an aesthetics clinic. That doesn't make the advice wrong, but it puts it in context. The cheapest part of the whole story is also the most boring - sunscreen every day, less sugar, no cigarettes and enough sleep, because skin makes collagen while you sleep.

Lasers can help repair one summer. But if every summer starts without sunscreen, the clinic will stay busy and the mirror will have less and less good news. How many of us still only wear SPF 50 at the beach?