Unconsciousness is a state which occurs when the ability to maintain an awareness of self and environment is lost. It involves a complete or near-complete lack of responsiveness to people and other environmental stimuli.
Loss of consciousness should not be confused with the notion of the psychoanalytic unconscious or cognitive processes (e.g., implicit cognition) that take place outside awareness, and with altered states of consciousness, such as delirium (when the person is confused and only partially responsive to the environment), normal sleep, hypnosis, and other altered states in which the person responds to stimuli.
Unconsciousness may occur as the result of traumatic brain injury, brain hypoxia (e.g., due to a brain infarction or cardiac arrest), severe poisoning with drugs that depress the activity of the central nervous system (e.g., alcohol and other hypnotic or sedative drugs), severe fatigue, anaesthesia, and other causes.
There is a theory that unconsciousness occurs when different regions of the brain inhibit one another.
Unconsciousness - first aid
Unconsciousness is when a person is unable to respond to people and activities. Doctors often call this a coma or being in a comatose state.
Other changes in awareness can occur without becoming unconscious. These are called altered mental status or changed mental status. They include sudden confusion, disorientation, or stupor.
Unconsciousness or any other sudden change in mental status must be treated as a medical emergency.
Unconsciousness can be caused by nearly any major illness or injury. It can also be caused by substance (drug) and alcohol use. Choking on an object can result in unconsciousness as well.
Brief unconsciousness (or fainting) is often a result from dehydration, low blood sugar, or temporary low blood pressure. It can also be caused by serious heart or nervous system problems. A doctor will determine if the affected person needs tests.
Other causes of fainting include straining during a bowel movement (vasovagal syncope), coughing very hard, or breathing very fast (hyperventilating).
The person will be unresponsive (does not respond to activity, touch, sound, or other stimulation).
The following symptoms may occur after a person has been unconscious:
- Amnesia for events before, during, and even after the period of unconsciousness
- Inability to speak or move parts of his or her body (see stroke symptoms)
- Loss of bowel or bladder control (incontinence)
- Rapid heartbeat (palpitations)
- Stupor (profound confusion and weakness)
If the person is unconscious from choking, symptoms may include:
- Inability to speak
- Difficulty breathing
- Noisy breathing or high-pitched sounds while inhaling
- Weak, ineffective coughing
- Bluish skin color
Being asleep is not the same as being unconscious. A sleeping person will respond to loud noises or gentle shaking. An unconscious person will not.
If someone is awake but less alert than usual, ask a few simple questions, such as:
- What is your name?
- What is the date?
- How old are you?
- Wrong answers or not being able to answer the question suggest a change in mental status.
If a person is unconscious or has a change in mental status, follow these first aid steps:
- Call or tell someone to call 911.
- Check the person's airway, breathing, and pulse frequently. If necessary, begin CPR.
- If the person is breathing and lying on their back, and you do not think there is a spinal injury, carefully roll the person toward you onto their side. Bend the top leg so both hip and knee are at right angles. Gently tilt their head back to keep the airway open. If breathing or pulse stops at any time, roll the person onto their back and begin CPR.
- If you think there is a spinal injury, leave the person where you found them (as long as breathing continues). If the person vomits, roll the entire body at one time to their side. Support their neck and back to keep the head and body in the same position while you roll.
- Keep the person warm until medical help arrives.
- If you see a person fainting, try to prevent a fall. Lay the person flat on the floor and raise their feet about 12 inches.
- If fainting is likely due to low blood sugar, give the person something sweet to eat or drink when they become conscious.
If the person is unconscious from choking:
- Begin CPR. Chest compressions may help dislodge the object.
- If you see something blocking the airway and it is loose, try to remove it. If the object is lodged in the person's throat, do NOT try to grasp it. This can push the object farther into the airway.
- Continue CPR and keep checking to see if the object is dislodged until medical help arrives.
- Do NOT give an unconscious person any food or drink.
- Do NOT leave the person alone.
- Do NOT place a pillow under the head of an unconscious person.
- Do NOT slap an unconscious person's face or splash water on their face to try to revive them.
When to Contact a Medical Professional
Call 911 if the person is unconscious and:
- Does not return to consciousness quickly (within a minute)
- Has fallen down or been injured, especially if they are bleeding
- Has diabetes
- Has seizures
- Has lost bowel or bladder control
- Is not breathing
- Is pregnant
- Is over age 50
Call 911 if the person regains consciousness but:
- Feels chest pain, pressure, or discomfort, or has a pounding or irregular heartbeat
- Cannot speak, has vision problems, or cannot move their arms and legs
To prevent becoming unconscious or fainting:
- Avoid situations where your blood sugar level gets too low.
- Avoid standing in one place too long without moving, especially if you are prone to fainting.
- Get enough fluid, particularly in warm weather.
- If you feel like you are about to faint, lie down or sit with your head bent forward between your knees.
If you have a medical condition, such as diabetes, always wear a medical alert necklace or bracelet.
Loss of consciousness - first aid; Coma - first aid; Mental status change; Altered mental status
What Is Unconsciousness?
Unconsciousness is when a person suddenly becomes unable to respond to stimuli and appears to be asleep. A person may be unconscious for a few seconds (fainting) or for longer periods of time.
People who become unconscious don’t respond to loud sounds or shaking. They may even stop breathing or their pulse may become faint. This calls for immediate emergency attention. The sooner the person receives emergency first aid, the better their outlook will be.
Part 2 of 7: Causes
What Causes Unconsciousness?
Unconsciousness can be brought on by a major illness or injury, or complications from drug use or alcohol abuse.
Common causes of unconsciousness include:
- a car accident
- severe blood loss
- a blow to the chest or head
- a drug overdose
- alcohol poisoning
A person may become temporarily unconscious (faint) when sudden changes occur within the body. Common causes of temporary unconsciousness include:
- low blood sugar
- low blood pressure
- syncope (loss of consciousness due to lack of blood flow to the brain)
- problems with the heart’s rhythm
- neurologic syncope (loss of consciousness caused by a seizure, stroke, or transient ischemic attack)
Part 3 of 7: Signs
Signs that a Person May Become Unconscious
Symptoms that may indicate that unconsciousness is about to occur include:
- sudden inability to respond
- slurred speech
- a rapid heartbeat
- dizziness or lightheadedness
Part 4 of 7: Emergency Care
Administering First Aid
If you see a person who has become unconscious, take these steps:
- Check whether the person is breathing. If they are not breathing, have someone call 911 immediately. If they are breathing, position the person on their back.
- Raise the person’s legs at least 12 inches above the ground.
- Loosen any restrictive clothing or belts. If the person doesn’t regain consciousness within one minute, call 911.
- Check the person’s airway to make sure there’s no obstruction.
- Check again to see if the person is breathing, coughing, or moving. These are signs of positive circulation. If these signs are absent, perform cardiopulmonary resuscitation (CPR) until emergency personnel arrive.
Cardiopulmonary resuscitation (CPR) is a way to treat someone when they stop breathing or their heart stops beating.
If a person stops breathing, call 911 or ask someone else to. Before beginning CPR, ask loudly, “Are you okay?” If the person doesn’t respond, begin CPR.
- Lay the person on their back on a firm surface.
- Kneel next to the person’s neck and shoulders.
- Place the heel of your hand over the center of the person’s chest. Put your other hand directly over the first one and interlace your fingers. Make sure that your elbows are straight and move your shoulders up above your hands.
- Using your upper body weight, push straight down on the person’s chest at least 1.5 inches for children, or 2 inches for adults. Then release the pressure. Repeat this procedure again up to 100 times per minute. These are called chest compressions.
To minimize potential injuries, only those trained in CPR should perform rescue breathing. If you haven’t been trained, perform chest compressions until medical help arrives.
If you are trained in CPR, tilt the person’s head back and lift the chin to open up the airway.
- Pinch the person’s nose closed and cover their mouth with yours, creating an airtight seal.
- Give two one-second breaths and watch for the person’s chest to rise.
- Continue alternating between compressions and breaths — 30 compressions and two breaths — until help arrives or there are signs of movement.
Part 5 of 7: Treatment
How Is Unconsciousness Treated?
If unconsciousness is due to low blood pressure, a doctor will administer medication by injection to increase blood pressure. If low blood sugar level is the cause, they may need something sweet to eat or a glucose injection.
Medical staff should treat any injuries that caused the person to become unconscious.
Part 6 of 7: Complications
Complications of Unconsciousness
Potential complications of being unconscious for a long period of time include:
- brain damage
If you received CPR while unconscious, you may have broken or fractured ribs from the chest compressions. Your doctor will X-ray your chest and treat any fractures or broken ribs before you leave the hospital.
Choking can also occur during unconsciousness. Food or liquid may have blocked your airway. This is particularly dangerous and could lead to death if it isn’t remedied.
Part 7 of 7: Outlook
What Is the Long-Term Outlook?
Your outlook will depend on what caused you to lose consciousness. However, the sooner you receive emergency treatment, the better your outlook will be.