breathholding

Breath-holding is the voluntary or involuntary suspension of breathing for a period of time. It occurs in ordinary life when someone holds their breath, in medical contexts such as apnea testing, and as part of activities like free diving. In children, breath-holding spells are reflex episodes that may occur after crying or injury.

Physiology: The drive to resume breathing is governed by arterial carbon dioxide (CO2) and oxygen (O2) levels. Rising CO2 and falling O2 stimulate chemoreceptors and trigger the urge to breathe. During breath-holding, the body can activate the mammalian diving reflex, especially in cold water, which slows the heart rate and redirects blood to vital organs. Hypoxia can impair function and lead to loss of consciousness if prolonged.

Types and contexts: Voluntary breath-holding includes static holds (no movement) and dynamic holds (with swimming). In trained divers, times of several minutes can be achieved. Medical contexts use apnea testing to assess brain activity. Breath-holding spells in children, usually cyanotic or pallid, are typically benign but warrant medical evaluation if frequent or prolonged.

Safety: Breath-holding carries risks such as hypoxia, fainting, seizures, and drowning. Hyperventilation before a hold can remove CO2 and delay the urge to breathe, increasing the risk of shallow-water blackout. Practices should be avoided alone or in unsafe environments and should be supervised when used for therapy or training.

Overview: Durations vary widely; untrained adults often hold from 30 seconds to a minute or two, while trained divers may reach several minutes. World records for static apnea exceed 10 minutes under specialized conditions. Variation depends on fitness, practice, hydration, and environmental factors.