The hair on your pillow — what your shedding pattern is telling you

The standard response tends toward reassurance that collapses quickly: you've changed shampoos, seasonal shedding is normal, everyone loses hair. And there's a version of dismissal that goes deeper — genetics, aging — delivered in a way that closes the conversation. Which is frustrating, because the shedding is happening now and it's different from what was happening before, and that difference has a cause, and the cause is almost always findable if someone looks.

Normal hair turnover is roughly 50 to 100 strands per day. Hair grows in cycles — anagen (active growth), catagen (transition), telogen (resting and shedding) — and at any given moment a healthy scalp has most follicles in anagen and a small fraction in telogen, cycling through. When significantly more than 100 strands shed daily and it's consistent rather than sporadic, and when you're noticing visible thinning rather than only individual strands, the follicular cycle has shifted. More follicles have moved into telogen than should be there. The question is what pushed them.

Telogen effluvium is the most common pattern of increased shedding, and its most defining feature is its timing. It happens two to three months after a physiological stressor — not immediately after, but delayed by the length of the telogen phase. Childbirth, major surgery, significant illness, rapid or extreme weight loss, severe psychological stress: these are the classic triggers. The body, under sufficient stress, shifts follicular priority — energy and resources get allocated elsewhere, growth-phase follicles get moved into resting phase in larger numbers than normal, and two to three months later the evidence appears in the drain and on the pillow. This delay is why people frequently can't identify a cause: the shedding happens when life has mostly normalized, and the stressor that caused it is weeks behind them. If you've had a difficult period in the past several months — medically, personally, physically — and the shedding started after it rather than during it, that pattern is meaningful.

Androgenic alopecia is a different pattern. It follows a distribution rather than presenting as diffuse shedding: in men, the classic recession at the temples and crown; in women, the widening part line and thinning at the vertex while the hairline stays mostly intact. It's driven by dihydrotestosterone — DHT — acting on genetically susceptible follicles, gradually miniaturizing them over years. It tends to be gradual rather than acute. It's the most common form of hair loss overall and has a genetic component, but the presence of genetic susceptibility doesn't mean the course is fixed. The biology of DHT and follicle miniaturization is addressable, and early intervention matters because the follicles, once miniaturized completely, are harder to recover.

Thyroid dysfunction is one of the most frequently missed systemic drivers of hair loss. Both hypothyroidism and hyperthyroidism affect the hair growth cycle, but the hypothyroid presentation is more common in the context of diffuse shedding: the follicles require thyroid hormone to stay in active growth phase, and with inadequate thyroid hormone more of them shift to resting phase, producing a diffuse thinning that can look like accelerated aging or stress response. The frustrating clinical reality is that hair loss is sometimes the only prominent early symptom of thyroid dysfunction, presenting before the more recognizable features. A TSH alone isn't always sufficient; free T3 and thyroid antibodies (anti-TPO and anti-thyroglobulin) add context that matters.

Iron deficiency without anemia is the other frequently missed driver, and it's important enough to be specific about. Ferritin — the body's iron storage protein — is the number that matters for hair, not hemoglobin. Hemoglobin can be normal while ferritin is depleted, and depleted ferritin is consistently associated with increased shedding in the literature. The exact threshold is debated, but many clinicians who work with hair loss consider ferritin below 30 to 40 ng/mL insufficient for optimal follicular function. A standard iron panel that returns "normal" may not include ferritin, and even when it does, the normal range is set by general population standards rather than hair-specific thresholds. Ask your prescribing provider specifically for a ferritin value when investigating shedding.

The protein story is related and similarly underappreciated. Hair is primarily keratin — protein. If dietary protein is inadequate, protein goes to more immediately essential functions and the follicles receive less. People on calorie-restricted diets, particularly those that are also low in animal protein, and people who have lost significant weight rapidly, are susceptible. Protein inadequacy doesn't produce a dramatic threshold event; it produces a gradual degradation in hair quality and growth rate that can look like aging or genetics when it's actually a substrate problem. This is particularly relevant in the context of GLP-1 use for weight loss, where rapid weight reduction without adequate protein support frequently produces telogen effluvium.

Perimenopausal and postmenopausal hormonal shifts are a significant driver of hair change in women that is often attributed to aging rather than to specific hormonal biology. Estrogen lengthens the growth phase of hair follicles — it's anti-androgenic at the follicular level and supports the anagen phase. Declining estrogen in the perimenopausal transition changes this balance, and many women in this window experience both increased shedding and a texture change — the hair becomes finer, less lustrous, less responsive — as a consequence of altered follicular signaling. PCOS-related androgen excess produces similar follicular effects through a different mechanism. Post-pill shedding — telogen effluvium triggered by stopping oral contraceptives — follows the same two-to-three-month delay pattern of other telogen effluvium triggers, because the pill's hormonal influence on the follicular cycle withdraws suddenly and the follicles respond with a synchronous shift to resting phase.

Medication effects are a real and documented contributor that's infrequently attributed correctly. Statins, antihypertensive medications (particularly beta-blockers), antidepressants, and anticoagulants have all been associated with increased shedding in some patients. The mechanism varies by drug class. If your shedding started or accelerated after a new medication, the timeline is worth tracking.

Where peptide approaches enter the picture with some evidence: GHK-Cu — a copper-binding tripeptide — has been studied topically for its effects on follicular health, with research showing it may support follicle enlargement, extend the growth phase, and stimulate collagen production around the follicle. The evidence base for topical GHK-Cu is more developed than for most topical peptides. It's not a replacement for addressing systemic drivers, but it has a reasonable mechanistic rationale as an adjunctive. Growth hormone axis peptides — which increase pulsatile GH release — may have indirect effects on hair through IGF-1, which has documented follicle-stimulating properties, and through improvements in sleep quality and recovery that affect the overall hormonal environment. These are conversations for a prescribing provider with a view of your specific pattern and labs.

The foundational interventions organize around pattern. For diffuse shedding: identify and address systemic causes — ferritin, thyroid, hormonal status, protein intake. For androgenic alopecia: early intervention with finasteride or minoxidil (both have real evidence) and dermatological evaluation if the course is rapid. For telogen effluvium: address the trigger if it's still active, support recovery if it isn't, and understand the several-month timeline before improvement is visible. For any pattern: specialist evaluation if the shedding is severe, accelerating, or accompanied by scalp symptoms.

The workup that's actually useful includes ferritin (specifically), TSH and thyroid antibodies, sex hormones depending on your demographics and pattern, vitamin D, and a clinical look at scalp pattern rather than only symptom description. The specific request matters. "Check my hair" doesn't produce a ferritin.

What increased shedding is signaling is that one or more systems involved in follicular health — hormonal, nutritional, inflammatory, or stress-response — have shifted past the threshold where the follicles maintain normal cycling. The shedding itself is a symptom of that shift, not the primary problem. Treating shedding without identifying the shift produces limited results. Understanding the shift is what produces the intervention that actually addresses it.