Experts challenge cortisol myths and everyday stress impact

Misconceptions about cortisol’s role in daily life are unlikely to justify extreme routines or constant self-tracking, as experts say brief stress rarely causes harmful hormone spikes and that worrying about levels may do more harm than good.

The hormone supports blood-sugar regulation by prompting glucose production, modulates inflammation, helps metabolise fat, protein and carbohydrate, influences blood pressure and mood, and assists recovery from acute illness; Angela Clow describes the normal “cortisol awakening response” that helps the brain become alert each morning rather than signalling stress.

Research published earlier this year indicates cortisol begins rising from its lowest point about three hours before waking, aligning with a daily rhythm that regulates multiple genes across tissues such as the brain, liver and immune system; levels then decline through the day with periodic bursts that aid normal function, which is why single at-home readings can mislead compared with multiple daily laboratory samples.

Laboratory stressors—from cold-water immersion and timed problem-solving to the Trier Social Stress Test—produce less dramatic cortisol responses than popular narratives suggest; as Stafford Lightman notes, “trying to stress a human is really difficult”, and Thomas Upton explains that immediate “fight-or-flight” sensations often reflect catecholamines like adrenaline, with cortisol following only if stress is strong or prolonged.

Chronic strain can disrupt the circadian pattern and lead to “flat-lining”, according to Clow, but cortisol itself is unlikely to alter appearance except in rare conditions such as Cushing’s syndrome; Upton adds that strenuous efforts like a marathon require a healthy cortisol response, so short-term exercise-related rises are not a problem.

Numbers in context: rises start roughly three hours before waking and brief bursts recur approximately every 90 minutes across the day.

Fads such as “cortisol cocktails” and routine monitoring are discouraged, with Lightman warning that tracking can create “worried well” behaviours amid wide individual variation; Niamh Martin notes that links between stress and poor health often reflect sleep loss, reduced exercise or changed eating patterns rather than cortisol acting as a singular cause.

Practical emphasis from the experts is to treat cortisol as a bystander while addressing lifestyle—sleep on a regular schedule, wake relatively early, limit night-time light, and use manageable activities such as walking, stretching, pilates, breath work and “micro-moments of joy”—recognising that the body’s stress response is usually protective.

29 July 2025 13:08 By London Health News Desk