The Image shows short-trimmed finger nails with some bite marks. Credit goes to Sue Bailey on Flickr.
Do nails grow faster during stress? Do nails on the feet grow slower? Do nails grow faster if you use nail polish?
I was somehow intrigued by these and other questions and I set out to search and found a great article from the year 1979 in the Journal of Investigative Dermatology. The article is called The Effect of Aging on the Rate of Linear Nail Growth and was written by Norman Orentreich, Jules Markofsky, and Joseph H Vogelman.
The authors propose that nail growth can be used for measurement of aging. Fingernail growth rate can be used to determine age! Turns out it depends mostly on age, but also on biorhythm, season, and circadian rythm.
So how fast do fingernails grow for different ages? The authors measured the nail growth of Caucasian males and females. In the graph below you find several curves:
A - 72 Caucasian males,
B - 185 Caucasian females,
C - One Caucasian male (from a different study),
X - (from yet another study) roughly 1000 people, Japanese and Caucasians by half, of both sexes.
Nails grow with a speed of between a quarter of a centimeter per month to about half a centimeter per month. Growth until around 20 years of age and after then becomes less with age.
Nail growth is greater in males than in females.
It might seem that for Japanese nail growth is less than for Caucasians, however without seeing the data from the other study it is risky to draw this conclusion.
What are the factors that determine or that are related with growth of nails?
See an excerpt from a table the authors compiled:
|Third Digit||First and fifth digits||Dietary supplement|
|Males||Females||Moderate emotional stress|
|Pregnancy||Lactation||Minor chronic illness|
|Piano Playing||Aging||Height and weight|
|Handedness||Malnutrition||Moderate weight change|
|Typing||Decreased Circulation||Skin color|
|Elevated Temperature||Lowered Temperature||Use of nail polish and remover|
Finger nails grow faster on the toes that you use more, they probably grow faster in summer than in winter.
Moderate stress doesn't seem to have any influence. Painting nails doesn't make them grow faster.
Enjoy. What is your nail growth? Please leave a comment below for questions and suggestions. If you liked this article you might also want to read about handwashing behavior (or: should I take the peanuts?).