Nocturnal vomiting is the involuntary expulsion of stomach contents that occurs during sleep or immediately upon waking. The human body has several protective mechanisms, including the gag reflex and a strong cough reflex, which normally prevent swallowed material from entering the windpipe. The epiglottis also closes over the trachea during swallowing to direct food and liquid into the esophagus. While these defenses function well when a person is conscious, sleep significantly lowers the sensitivity of these reflexes, increasing the risk associated with nocturnal vomiting.
Understanding Aspiration Risk
The greatest concern when vomiting occurs during sleep is pulmonary aspiration, which is the inhalation of stomach contents into the lungs. This happens because protective reflexes are partially suppressed during deep sleep, allowing material to enter the lower respiratory tract. The immediate physiological response to aspiration is typically a sudden, violent coughing fit as the body attempts to clear the foreign material.
The long-term consequences of aspiration are divided into two primary conditions, depending on the nature of the inhaled material. If the aspirate is mostly acidic stomach fluid (pH below 2.5), it causes chemical pneumonitis, a severe inflammatory reaction. This non-infectious condition results from a corrosive burn to the lung tissue, leading to rapid onset of breathing difficulty and lung injury.
If the inhaled material contains bacteria, it can lead to aspiration pneumonia, a serious lung infection. Although stomach acid kills most bacteria, the contents often contain pathogens that trigger an infection once settled in the lungs, manifesting with fever and a productive cough. The risk of aspiration is increased when a person has an altered level of consciousness, which significantly impairs the ability to coordinate protective reflexes.
Common Reasons for Vomiting While Asleep
Several acute or chronic factors can trigger vomiting severe enough to interrupt sleep. One common cause is excessive alcohol consumption, which increases risk by irritating the stomach lining and prompting gastric acid production. The liver also struggles to metabolize the toxic byproduct acetaldehyde, leading the brain to initiate vomiting to expel the poison.
Acute severe illnesses are another frequent trigger. Gastroenteritis, commonly referred to as the stomach flu, causes inflammation of the gastrointestinal tract, resulting in sudden, forceful vomiting and diarrhea. Similarly, food poisoning can cause an isolated episode of vomiting as the body attempts to eliminate ingested toxins.
Chronic digestive conditions also increase the likelihood of nocturnal vomiting. Gastroesophageal Reflux Disease (GERD) is a disorder where the lower esophageal sphincter is weak, allowing stomach contents to flow back up, an effect worsened by lying flat. Gastroparesis, or delayed gastric emptying, causes food to remain in the stomach for an extended time, leading to severe nausea and vomiting, often prevalent at night or early morning.
Immediate Steps and When to Seek Care
If vomiting occurs while a person is asleep or has reduced consciousness, the immediate priority is ensuring the airway is clear. Quickly roll the person onto their side into the recovery position, allowing any remaining vomit to drain out of the mouth by gravity. If the person is conscious, encourage them to sit up and cough forcefully to clear their throat and lungs.
After the event, monitor for warning signs of aspiration, especially if the person was not fully alert. Signs of airway compromise include persistent coughing, wheezing, noisy or raspy breathing, or a bluish tint to the lips or face, indicating a lack of oxygen. Developing a fever is a delayed but serious indicator that aspiration pneumonia may be developing.
Symptoms of aspiration pneumonia typically develop within 24 to 72 hours following the event. Emergency medical attention is necessary if a fever above 101°F develops, if shortness of breath persists, or if the person begins coughing up foul-smelling or discolored sputum. For those at chronic risk, preventative steps include not eating within two to three hours of bedtime and elevating the head of the bed by six to nine inches with blocks or a wedge pillow to utilize gravity in keeping stomach contents down.