Circadian Rhythm and Nail Growth
Nail Growth and Changes with Aging and Circadian Rhythm
The rate of nail growth decreases as we age, and is estimated to decrease by up to 50% over a life span. The rate of linear nail growth increases until our 30s, after which the rate steadily declines. The nails can undergo other changes with age as well, including changes in curvature, thickness, smoothness, and even composition.[2,3]
Nail Changes Seen in the Elderly
Nail disorders and changes in appearance are common findings in the elderly. Multiple factors can contribute, including poor blood circulation, susceptibility to fungal nail infections, or the result of other skin diseases, medications, and nutritional deficiencies.
Normal nail changes seen with aging
- Chemical composition changes – increased amounts of calcium and decreased iron
- Nail growth changes – rate of nail growth decreases in the elderly
- Nail color changes – nails may appear pale, dull, opaque, with color ranging from white or yellow to brown and grey
- Contour changes – decreased longitudinal curvature and increased transverse convexity such that the nail may seem flattened or spooning
- Surface texture changes – may include striations, roughness, or nail splitting
- Thickness changes – nail plate thickness could increase or decrease in elderly
Common Nail Disorders in the Elderly
- Brittle nails – lower than normal water content and can result in rough nail plates, fragile and easily breakable nails, and nail splitting
- Onychomycosis – fungal infections of the nails
- Onychauxis – an overgrowth of the nail including thickening, discoloration, and loss of translucency of nail plate
- Onychogryphosis – ingrown nails
- Onychophosis – a tissue growth, or callus, in between nail folds and the nail plate from repeated minor trauma
- Splinter hemorrhages – tiny blood clots that appear as dark or black spots on the nail, most often a result of a nail injury
- Neapolitan nail - absent lunula with three horizontal bands of white, pink, and opaque discoloration
Circadian Rhythm and Aging
The circadian rhythm is a biological clock influenced by cycles of light and dark during a 24 hour period that governs normal biological functions throughout the body. It is believed that the normal circadian rhythm can change with aging. Melatonin is a hormone that plays a vital role in the regulation of circadian rhythms. By measuring the levels of melatonin in salivary secretions, researchers have shown that nighttime melatonin decreases and daytime melatonin is increased in the elderly compared to younger people. The change in melatonin likely leads to altered circadian rhythm.
Circadian Rhythm and Nail Growth
Components within the skin, including oil glands, hair follicles, and skin cells have patterns based on the circadian rhythm. In addition, nail growth has been shown to oscillate in a day-night pattern according to the circadian rhythm. Nail growth has been shown to be lower during the night time and almost five times higher during the day, suggesting a possible relationship with the circadian rhythm.
While we can clearly see a relationship between nail growth and aging, as well as circadian rhythm and aging, the connection between nail growth and circadian rhythm is a fascinating concept that has yet to be clearly explained for us.
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