Sleep
Sleep is when the body carries out much of its repair. Learn what research says about sleep, the body clock and hair, and where the evidence is still thin.
Supriya Bhandary
Founder, Soumm · 4 September 2026 · Updated 14 October 2026
What does sleep do?
Sleep is a recurring state of reduced awareness during which the body and brain carry out much of their repair and regulation, including hormone release and immune activity. Sleep experts advise most adults to aim for seven or more hours a night. (Watson et al., 2015)
Sleep and hair
Hair follicles have their own body clock, and laboratory studies show that clock genes help regulate the timing of the hair cycle. (Al-Nuaimi et al., 2014)
A large population study linked sleep disorders with a higher risk of alopecia areata, an autoimmune form of hair loss. (Seo et al., 2018) These findings show associations, not proof that poor sleep causes hair loss.
In practice
Regular, sufficient sleep supports stress recovery and overall health. Hair loss alongside ongoing poor sleep or tiredness is worth discussing with a doctor, as conditions such as thyroid disease or iron deficiency can affect both.
See also: Stress, Cortisol, Hair Cycle.
Sources
Al-Nuaimi Y, Hardman JA, Bíró T, et al. A meeting of two chronobiological systems: circadian proteins Period1 and BMAL1 modulate the human hair cycle clock. J Invest Dermatol. 2014;134(3):610–9.
Seo HM, Kim TL, Kim JS. The risk of alopecia areata and other related autoimmune diseases in patients with sleep disorders: a Korean population-based retrospective cohort study. Sleep. 2018;41(9):zsy111.
Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. J Clin Sleep Med. 2015;11(6):591–2.
Questions
Research links poor sleep with stress and with some forms of hair loss, but it has not shown that short sleep alone causes hair loss.
Sleep experts recommend seven or more hours a night for most adults.
There is no evidence that night-time oiling works better than daytime. Choose the time that lets you take it slowly and wash out thoroughly.