What is a common sign of aging in nails?

Lengthwise, wavy ridges in nails are indeed a common sign of aging. As the body ages, changes to the structure and health of the nails can occur, leading to the development of these ridges. This can be due to a variety of factors including reduced moisture and changes in nail cell turnover. Additionally, the underlying mechanisms that support nail growth may become less efficient, contributing to the appearance of these ridges.

Nail surface discoloration and conditions like pitting and onycholysis can also be caused by various health issues or environmental factors, but they are not specifically associated with the natural aging process. Similarly, bitten nails tend to result from habits often related to stress or anxiety, rather than aging. Therefore, the presence of lengthwise, wavy ridges is a more direct indicator of the aging process in nails.