The reason why we tan in the sun, it’s because your skin cells are commiting suicide.
When your skin gets sunburned, it’s because your skin cells are basiclly commiting suicide so that they don’t becomes cancerous.
Sunburns may seem harmless enough (albeit annoying), but did you know that they’re actually a type of radiation burn?
Sunburns actually cause a huge amount of damage on a cellular level.
Sunlight is more than just nature’s way to wake you up in the morning. Sunlight is actually a form of electromagnetic radiation, along with radio waves, microwaves, and radioactive waves.
By the time sunlight reaches you on Earth after traveling through space, its radiation comes in two types: Ultraviolet A (UVA) and Ultraviolet B (UVB).
In small doses, sunlight is beneficial. It allows your body to create the necessary nutrient vitamin D and sets your body on track for normal circadian rhythms i.e 24-hour sleep/wake cycles.
Most sunlight is composed of UVA radiation, which has slightly less energy than more damaging UVB rays.
UVA rays are less likely to give you a sunburn, but they can penetrate deeper into your skin and cause more cumulative damage over time in the form of saggy, aging skin . UVB rays, on the other hand, contain more energy that can harm your skin immediately.
UV radiation basically damages skin by transferring energy to molecules in your skin, such as DNA, fat, proteins, etc. These molecules, which are already in their proper arrangement, absorb this energy. If the molecules absorb enough energy, the bonds holding them together can break, forming a new shape completely.
UV radiation damage to DNA is a particular problem. DNA is a huge molecule and actually quite fragile. When a molecule of DNA is present in a cell, it resembles a zipper: it has two strands, with each strand tightly bound to corresponding molecules on the opposite side, called bases.
There are four different bases; adenine, guanine, cytosine, and thymine. Thymine and cytosine, when occurring right next to each other, are particularly susceptible to forming dimers. When sunlight hits these sections, thymine and cytosine will “let go” of the other side of the chain and form bonds with each other. Suddenly, the DNA code is broken, and if this DNA section codes for a specific protein, it won’t make the right protein anymore.
The good news is that each cell has its own small army of molecules which can go in and fix the broken DNA section. The bad news is that when your skin is out in full sun, this process is happening on an epic scale and sometimes the small army can’t keep up with the damage.
If a cell becomes too damaged, it also has its own suiside function: it will go through a process called apoptosis and essentially commit suicide. This seems harsh, but without it, too many damaged cells can accumulate and soon your skin wouldn’t work at all like it’s supposed to.
There’s a bit of a catch-22 though: your own DNA codes for a self destruct function and if that section of your DNA is damaged or if a damaged DNA section just happens to evade repair, the auto-delete won’t function like it’s supposed to. The cell won’t kill itself, and it might even start growing out of control. This is how skin cancer forms.