Hair growth occurs in cycles and is controlled by your genes, hormones, and age. The hair growth cycle consists of three main phases: anagen, catagen, and telogen. The anagen phase is the active growth phase where hair follicles produce new hair. This phase can last 2-7 years. The catagen phase is a short transitional phase that signals the end of the active growth phase. This phase lasts about 2-3 weeks. The telogen phase is the resting phase where hair stops growing and eventually falls out. This phase lasts around 2-3 months. After this, the hair follicle enters the anagen phase again and the cycle repeats itself. On average, about 85-90% of hair follicles are in the anagen phase while only 10-15% are in the telogen phase.
There are many factors that can influence and stimulate the hair growth cycle. Understanding what stimulates hair follicles to grow can help develop strategies to treat hair loss or promote hair growth. Some key stimulators of hair follicle growth include:
Several hormones play a role in regulating the hair growth cycle:
– Androgens – Androgens like testosterone, dihydrotestosterone (DHT), and androsterone stimulate hair growth. They bind to androgen receptors in hair follicles and prolong the anagen phase. Higher levels of androgens are linked to increased hair growth.
– Estrogen – Estrogen extends the anagen growth phase leading to longer hair growth. Low estrogen levels in menopausal women contribute to thinning hair.
– Prolactin – This hormone extends the anagen phase and stimulates hair growth. Excess prolactin production can cause excess hair growth known as hirsutism.
– Thyroid hormones – Both hypothyroidism and hyperthyroidism can disrupt the hair growth cycle leading to hair loss. Proper thyroid hormone levels help maintain normal hair growth.
Growth factors are proteins that bind to receptors on hair follicle stem cells and stimulate growth. Key growth factors include:
– Vascular endothelial growth factor (VEGF) – Boosts hair follicle blood supply to provide nutrients for growth.
– Insulin-like growth factor 1 (IGF-1) – Prolongs anagen phase and increases follicle size.
– Fibroblast growth factor 9 (FGF9) – Maintains anagen phase in hair follicles.
– Hepatocyte growth factor (HGF) – Activates hair follicle stem cells and induces growth.
Adequate nutrition provides building blocks for hair growth:
– Protein – Keratin protein makes up 97% of hair. Inadequate protein intake leads to reduced hair growth.
– Iron – Iron carries oxygen to follicles. Low iron (anemia) is linked to hair loss.
– Zinc – Zinc stimulates hair follicle receptors and is vital for DNA and protein synthesis.
– Biotin – Biotin deficiency can cause brittle hair and hair loss.
– Fatty acids – Omega-3 and omega-6 fatty acids nourish the scalp and promote healthy hair.
Some natural compounds can stimulate hair growth:
– Caffeine – A stimulant that prolongs anagen phase by blocking DHT production. Found in coffee or hair products.
– Melatonin – Regulates hair cycle timing and prolongs anagen phase to stimulate growth.
– Biotin – A B vitamin that aids keratin production. Supplements may boost hair growth.
– Coconut oil – Contains lauric acid to nourish hair follicles.
– Ginseng – Contains saponins that stimulate follicles and boost circulation.
– Onion juice – Contains sulfur and phenols to stimulate hair regrowth.
Medications and Supplements
– Minoxidil – Topical drug that prolongs anagen phase. It is the only FDA-approved drug for treating hair loss.
– Finasteride – Oral DHT inhibitor used for hair loss treatment in men.
– Spironolactone – Oral drug that blocks androgens and is used for female hair loss.
– Biotin supplements – Some evidence shows high dose biotin (2500 mcg/day) may stimulate hair growth.
– Fo-Ti – Herbal supplement derived from Polygonum multiflorum. Contains antioxidants that may stimulate follicles.
– Vitamin D – Research links vitamin D deficiency to hair loss. Supplements may support growth.
Gentle massage of the scalp can stimulate hair follicles in several ways:
– Improves scalp blood circulation to carry nutrients to follicles
– Provides gentle mechanical stress that activates growth pathways
– Helps remove dead skin cells and buildup around follicles
– Releases relaxing neurotransmitters that reduce stress hormones
– Oils used during massage nourish follicles and enhance stimulation
Perform scalp massage in small circular motions for 4-5 minutes daily. Be gentle to avoid damaging follicles. Oils like coconut, almond or argan oil can enhance the benefits.
Low-level laser light (LLLT) devices have been FDA-cleared for stimulating hair growth. The mechanisms include:
– Increases ATP production to energize follicles
– Boosts blood flow and nutrient supply to follicles
– Activates transcription factors that induce growth
– Reduces inflammation around follicles
Use of LLLT helmets and caps can stimulate follicles and promote new growth. However, effectiveness varies based on factors like wavelength, power, and duration of treatment. Consult a dermatologist before trying laser therapy.
Microneedling creates microscopic channels in the skin to boost absorption of hair stimulating compounds. It enhances hair growth by:
– Improving penetration of topical minoxidil into scalp
– Triggering stem cell activation and new growth
– Increasing blood circulation and nutrient supply
– Reducing inflammation and oxidative stress
– Releasing growth factors through microinjury
Microneedling should be done professionally using sterile needles. Over-the-counter rollers carry risk of infection. Use topical minoxidil after microneedling for added stimulation.
Platelet-rich plasma (PRP) contains concentrated growth factors obtained from a patient’s own blood. PRP injections work by:
– Supplying a high dose of growth factors when injected into scalp
– Activating stem cells and inducing new growth
– Improving hair follicle vascularization
– Reducing miniaturization of follicles
– Providing proteins and nutrients to nourish follicles
Multiple PRP treatments are needed every 1-3 months. Results vary but can last over a year. PRP along with other treatments like microneedling enhances stimulation.
Light therapy uses LED light energy to stimulate hair follicles. Red and blue wavelengths are most effective. Mechanisms include:
– Increasing ATP production to energize follicles
– Improving cell metabolism and protein synthesis
– Boosting blood flow and nutrient supply
– Reducing inflammation around follicles
Hand-held LED devices or hood/caps can be used. Treatments are required 2-3 times a week for best results. Light therapy often works best along with minoxidil.
Regular exercise stimulates hair growth through several mechanisms:
– Increases blood circulation including to the scalp
– Boosts testosterone levels in men and women
– Regulates hormones and growth factors
– Reduces stress hormone cortisol
– Improves nutrition delivery to follicles
Aim for at least 150 minutes of moderate exercise per week. Weight training boosts testosterone. Yoga and pilates reduce stress hormones. Scalp massage after exercise may further stimulate follicles.
Healthy Scalp Environment
Creating optimal scalp conditions promotes hair growth:
– Use gentle products without sulfates or parabens
– Reduce dandruff and inflammation with anti-fungal shampoos
– Avoid very hot water which can dry out follicles
– Reduce scalp tension from tight hairstyles
– Eat a balanced diet with protein, iron, zinc and vitamins
– Treat medical conditions like thyroid disorders
– Drink enough water and get 7-9 hours sleep nightly
– Reduce stress with meditation, massage, yoga
– Avoid smoking which constricts blood vessels
Hair growth is a complex process that involves the hair cycle, hormones, growth factors, scalp health and good nutrition. Key stimulators include hormones like androgens, medications like minoxidil, growth factors in PRP, and techniques like massage and microneedling. Creating a healthy scalp environment also optimizes conditions for hair follicles to grow. A multifaceted approach combining lifestyle changes, natural stimulators and treatments provides the best strategy for stimulating hair growth. Consistency is vital as hair growth is a gradual process. Work with a dermatologist to develop a customized hair growth plan.