Randomly falling asleep isn’t random—look for this trigger.

Randomly falling asleep isn’t random—look for this trigger

It’s unsettling to drift off unexpectedly, especially if it interferes with work, driving or daily activities. While occasional drowsiness happens to everyone, “randomly falling asleep” can point to an underlying issue that needs attention. One key culprit in people with liver disease is hepatic encephalopathy (HE)—a change in brain function caused by toxins your damaged liver can’t clear. Recognizing the warning signs and triggers can help you get timely treatment and avoid serious complications.

What is hepatic encephalopathy?
Hepatic encephalopathy occurs when the liver can’t remove toxins (like ammonia) from the blood. These substances build up and affect your brain, leading to a spectrum of symptoms from mild confusion to deep sleep or coma. According to the Working Party at the 11th World Congress of Gastroenterology (Ferenci et al., 2002) and updated by the European Association for the Study of the Liver (EASL, 2018), HE is classified as:

• Minimal HE: subtle thinking and coordination changes, often unnoticed without specialized tests
• Overt HE: clear symptoms such as sleepiness, confusion, personality changes or asterixis (flapping tremor)

Why you might be randomly falling asleep
When HE worsens, the first sign for many is excessive daytime sleepiness or suddenly drifting off. Unlike normal tiredness, this sleepiness:

• Comes on quickly, without obvious fatigue or long hours awake
• Isn’t relieved by a nap or good night’s rest
• May be accompanied by brief confusion or disorientation upon waking

What triggers hepatic encephalopathy?
HE can wax and wane depending on factors that worsen toxin buildup. Common triggers include:

• Gastrointestinal bleeding
– Ulcers or varices (enlarged veins) in the gut release blood that bacteria break down into ammonia.
• Infection
– Even a minor urinary tract or lung infection can inflame the body and tip the balance.
• Electrolyte disturbances
– Low potassium or sodium levels disrupt how your brain cells handle toxins.
• Dehydration
– Reduced blood volume concentrates toxins in the bloodstream.
• Constipation
– Slower gut transit allows more toxin production.
• Sedatives or narcotics
– Medications that depress the central nervous system can worsen sleepiness.
• High-protein meals or supplements
– Too much dietary protein raises ammonia production (though severe restriction isn’t usually needed).

Early warning signs beyond sleepiness
Keep an eye on any gradual changes that may precede or accompany suddenly falling asleep:

• Mild confusion, difficulty focusing or short-term memory lapses
• Mood swings, irritability or apathy
• Slurred speech or slowed movements
• Poor coordination or “drunken” gait
• Asterixis: brief, involuntary hand flaps when you extend your wrists

Diagnosing the cause
If you have liver disease and start randomly falling asleep, your doctor will:

1. Review your medical history and recent changes (infections, medications, bleeding)
2. Perform a physical exam, looking for signs of liver disease (enlarged spleen, jaundice) and asterixis
3. Order blood tests to check ammonia levels, electrolytes, kidney function and markers of infection
4. Use mental-status tests (e.g., number-connection tests) to detect minimal HE
5. Rule out other causes of sleepiness (sleep apnea, thyroid problems, depression)

Treating hepatic encephalopathy
The goal is to remove or reduce triggers and clear toxins from your system. Standard approaches (Cordoba, 2014; EASL, 2018) include:

• Lactulose
– A nonabsorbable sugar that draws ammonia into the gut, where bacteria convert it into non-toxic compounds.
– Dosage is adjusted so you have two to three soft bowel movements daily.
• Rifaximin
– An antibiotic that targets ammonia-producing gut bacteria, often added if lactulose alone isn’t enough.
• Correcting electrolyte imbalances
– Replenish potassium, sodium or magnesium as needed.
• Treating precipitating factors
– Control infections with antibiotics, stop gastrointestinal bleeding, address dehydration.
• Medication review
– Avoid or adjust sedatives, narcotics or other drugs that worsen drowsiness.
• Nutritional support
– Maintain a balanced diet with moderate protein intake; consider small, frequent meals.

Prevention and lifestyle tips
You can dramatically reduce the risk of HE flares by:

• Sticking to your prescribed medications (lactulose, rifaximin)
• Monitoring your weight and fluid intake to avoid dehydration
• Eating small meals throughout the day, focusing on vegetable protein and complex carbs
• Avoiding alcohol completely
• Checking in with your healthcare team whenever symptoms change
• Learning early signs so you can act before sleepiness escalates

When to seek immediate help
Randomly falling asleep can sometimes escalate rapidly. Seek urgent medical care if you experience:

• Inability to wake up or deep unresponsiveness
• Seizures or sudden, severe confusion
• Signs of gastrointestinal bleeding (vomiting blood or black, tarry stools)
• High fever, chills or signs of a serious infection

Free online support
If you’re not sure what’s causing your sudden sleepiness, consider doing a free, online symptom check for randomly falling asleep. This can help you decide if you need prompt medical attention.

Speak to a doctor
Randomly falling asleep shouldn’t be ignored—especially if you have liver disease or other health concerns. Talk to your doctor about any troubling symptoms. If you experience severe drowsiness, confusion, bleeding or infection signs, seek emergency care immediately. Your health matters, and early action can prevent serious complications.