- Hair is technically dead - the only bit that's living is in your scalp
- Hair consists mainly of keratin, which is also responsible for the elasticity of fingernails.
- A single hair has a thickness of 0.02 - 0.04mm, so that 20 - 50 hair strands next to each other make one millimetre.
- Hair is the fastest growing tissue in the body, second only to bone marrow
- Humidity stretches the hair
- The trait for baldness can be passed down through paternal or maternal genes.
- Combing is less detrimental than brushing
- Correct shampooing will not dry out the hair
- Frequent washing does not increase loss of hair
- Hair grows faster in warm weather
- Elderly people have slower hair growth and diminished hair density
- Cutting hair does not influence its growth
- Split ends can not be repaired and need to be cut
- Wet hair should not be rubbed since hair is very sensitive
- The average scalp has 100,000 strands, or just fewer than 1000 per square inch.
- A blonde head of hair has usually much more strands than red or dark hair heads.
- 90% of scalp hairs are growing and 10% are resting.
- It is normal to lose 100 hairs per day from the scalp.
- Hormone imbalance and crash dieting can trigger temporary hair loss.
- Depending on the individual, the hair follicle can grow up to 1 metre in length before it stops growing.
- When you are born, you have around 1000 follicles per square centimetre. When you reach 25, it falls to around 600 per square centimetre but can vary depending on the individual. By your mid 30s to 40s, your hair follicles will reduce to around 300 or less. After that, there won't be any significant drop.
Krause, K; Foitzik, K (2006). "Biology of the Hair Follicle: The Basics". Seminars in Cutaneous Medicine and Surgery 25
Sabah, NH (1974). "Controlled stimulation of hair follicle receptors.". Journal of applied physiology 36 (2): 256–7. PMID 4811387