Dermal skin cells do not divide as quickly as they once did as the skin begins to age. When there is reduced cell division, the skin takes longer to rejuvenate. As a result, it begins to thin due to a lack of hardiness in the skin, according to WebMD.
As stated by Medline Plus, while cell division reduces in the dermal layer of the skin, degradation of fatty cells in the hypodermal layer of the skin also occurs. This causes the skin to sag. The slightest physical contact, such as a bump against a table, can rupture blood vessels due the lack of protective cushioning provided by the fatty cells in the hypodermal layer of the skin. This leads to thin skin bruising more easily.
Thin skin can also be attributed to genetics, according to Mayo Clinic. Thin skin can be hereditary and is likely to occur if one's parents had it. Altering the genetic factors that contribute to thin skin is impossible. However, there are some causal behaviors that can control the non-genetic factors of skin thinning.
The National Institute on Aging states that overexposure to the sun's ultraviolet rays breaks down the dermal cells in the skin, which contributes to the thinning of the skin. Limiting time spent in the sun and using sunscreen can reduce damage to these skin cells, according to the Mayo Clinic.