Hair continues to grow while a person is in a coma, although the rate of growth may change. A coma is a state of deep unconsciousness where a person is unresponsive and cannot be easily awakened. The body remains alive, performing basic functions necessary for survival, such as circulation, respiration, and cellular division. Hair growth is a localized, cellular process that proceeds independently of brain activity and consciousness.
The Biological Mechanics of Hair Growth
Hair growth happens in a continuous, cyclical process involving four distinct stages: anagen, catagen, telogen, and exogen. The anagen phase is the active growth period, where cells in the hair follicle’s root divide rapidly, producing the hair shaft. This phase can last two to seven years for scalp hair, determining the maximum length the hair can achieve. The catagen phase is a brief transition stage lasting about two to three weeks, during which growth stops and the follicle shrinks. Finally, the telogen phase is a resting period of two to four months where the hair remains in the follicle without growing, followed by the exogen phase, where the old hair falls out to make room for a new hair beginning the cycle.
Coma State and Cellular Function
Despite the loss of consciousness, medical support maintains essential life processes. The heart continues to beat, blood circulates, and metabolism continues, ensuring oxygen and nutrients are delivered throughout the body, including to the hair follicles. Hair growth is a metabolically demanding process, requiring energy and building blocks like proteins and vitamins. Medical teams ensure continuous nutrition, often intravenously, to support basal cellular functions. As long as the hair follicle receives a steady supply of nutrients and oxygen, the cycle of cellular division and growth in the anagen phase will persist.
Illness, Medication, and Growth Rate
Although hair growth does not stop entirely, its rate and density can be significantly modified in a comatose or critically ill patient. Severe underlying illness, like sepsis or major trauma, creates intense systemic inflammation that diverts resources away from non-essential functions like hair production. This stress can prematurely push a large number of hair follicles from the active anagen phase into the resting telogen phase. This stress-induced shedding is known as Telogen Effluvium, and it can become noticeable several months after the illness or coma resolves, resulting in significant hair loss. Certain strong medications administered during critical care, such as high-dose steroids or chemotherapy drugs, can also disrupt the hair cycle, and poor nutrition, if not adequately managed, can slow the growth rate by limiting the availability of necessary proteins and minerals.
Related Phenomenon: Nail Growth
Similar to hair, nail growth also continues during a coma. Nails are primarily composed of the protein keratin and are formed by the continuous division of specialized cells in the nail matrix, located at the base of the nail. This cell division constantly pushes the hardened nail plate forward.
Unlike hair, which grows in cycles of growth and rest, the nail matrix produces cells continuously, meaning growth is more constant. However, the nail growth rate can be slowed down by severe illness, poor circulation, or nutritional deficiencies experienced during the critical care period.
Beau’s Lines
Survivors of critical illness may notice ridges or grooves in their nails, called Beau’s lines. These lines reflect a temporary halt or slowdown in cell division that occurred during the peak of their sickness.