Anaphylactic shock is a severe, life-threatening allergic reaction that affects multiple organ systems simultaneously. This medical emergency occurs when the body overreacts to a trigger, leading to a sudden, systemic cascade of events. Anaphylaxis can certainly occur during sleep. The primary danger at night is not the timing of the reaction itself, but the delayed recognition and response due to the person being unconscious.
Understanding the Systemic Reaction
Anaphylaxis occurs when the immune system releases chemical mediators, such as histamine, from mast cells and basophils. This rapid chemical release causes a systemic inflammatory response that progresses quickly, often within minutes. The resulting widespread effects include a sudden drop in blood pressure, which is characteristic of anaphylactic shock.
The reaction also causes the airways to constrict and swell, making breathing difficult or impossible. This systemic collapse deprives the body’s vital organs of oxygen and adequate blood flow. The severity of this multi-system reaction establishes the condition as a medical emergency.
Common Nocturnal Triggers
Anaphylactic reactions during sleep are often caused by triggers with a delayed-onset mechanism or those introduced directly into the sleeping environment. A prime example is Alpha-gal syndrome (AGS), a food allergy to carbohydrates found in mammalian meat. Unlike typical food allergies, AGS symptoms are frequently delayed by three to six hours after ingestion, meaning a late dinner could result in a reaction in the middle of the night.
Other food allergens may cause nocturnal symptoms if a large, fatty meal is consumed late, which slows digestion and allergen absorption. Hidden environmental allergens also pose a risk, such as insect venom from nocturnal bites or severe reactions to dust mites or pet dander in the bedding. Furthermore, certain medications taken before bed, including new prescriptions or delayed-release drugs, can trigger a reaction hours after they were swallowed.
Recognizing Symptoms While Unconscious
Because the individual is asleep, the ability to self-identify initial symptoms is lost. Therefore, recognition of subtle physical changes by a partner or cohabitant is crucial. Anaphylaxis symptoms should be severe enough to wake the person, but this is not guaranteed, and progression can be rapid. Signs such as sudden, loud wheezing or deep gasping for air point to airway constriction and swelling.
Unusual restlessness, intense itching, or suddenly waking with widespread hives or angioedema (swelling of the lips, face, or throat) indicate a systemic reaction. Gastrointestinal symptoms, like sudden vomiting or diarrhea, can also occur, sometimes without the common skin symptoms, such as in Alpha-gal syndrome. Any combination of these signs should be considered a medical emergency, as they can quickly progress to a weak and rapid pulse or loss of consciousness.
Nighttime Emergency Response Planning
For individuals at risk for anaphylaxis, planning is necessary to manage a potential nighttime event. The Epinephrine Auto-Injector (EpiPen) must be kept immediately accessible, ideally on a bedside table, and never stored in another room or cabinet. Having two doses readily available is recommended, as approximately 25% of people may require a second dose after the first.
Family members, partners, or cohabitants should be trained on how to recognize subtle nocturnal signs and how to administer the auto-injector correctly. Upon recognizing symptoms, the immediate action is to administer the epinephrine and then call emergency services. The person should be instructed to lie flat, or sit up if breathing is difficult, and should not be allowed to stand or walk.