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Diseases & Conditions A - Z
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Consciousness – Decreased

What Is Decreased Consciousness?

Alertness and being oriented to place and time are major characteristics of consciousness. Alertness means that you are able to respond appropriately to the people and things around you. You are oriented when you know who you are, where you are, where you live, and what time it is.

When consciousness is decreased, your ability to remain awake, aware, and oriented is impaired. Impaired consciousness is a medical emergency.

Consciousness and the Brain

The brain is the main organ responsible for maintaining consciousness. Your brain requires adequate amounts of oxygen and glucose in order to function properly. Many substances you consume affect your brain chemistry and can help to maintain or decrease consciousness.

For example, caffeine is a stimulant, which means that it stimulates brain activity. Caffeine can be found in many foods you eat every day, such as coffee, soda, and chocolate. Painkillers and tranquilizers make you drowsy. This side effect is a form of impaired consciousness. Diseases that damage your brain cells can also cause impaired consciousness. Coma is most severe level of consciousness impairment.

Symptoms of Decreased Consciousness

Levels of impaired consciousness include: confusion, disorientation, delirium, lethargy, stupor, and coma.


Confusion is marked by the absence of clear thinking and may result in poor decision-making.


Disorientation is the inability to understand how you relate to people, places, objects, and time. The first stage of disorientation is when you are disoriented with respect to time (years, months, days). This is followed by disorientation with respect to place, which means you may not know where you are. Loss of short-term memory follows disorientation with respect to place. The most extreme form of disorientation is when you lose the memory of who you are.


If you are delirious, your thoughts are confused and illogical. People who are delirious are often disoriented. Their emotional responses range from fear to anger. People who are delirious are often highly agitated.


Lethargy is a state of decreased consciousness that resembles drowsiness. If you are lethargic, you may not respond to stimulants like the sound of an alarm clock or the presence of fire.


Stupor is a deeper level of impaired consciousness in which it is very difficult for you to respond to any stimuli, except for pain.


Coma is the deepest level of impaired consciousness. If you are in a coma, you cannot respond to any stimulus, not even pain.

Symptoms that may be associated with decreased consciousness are:

  • seizures
  • loss of bowel or bladder function
  • poor balance
  • falling
  • difficulty walking
  • fainting
  • lightheadedness
  • irregular heart beat
  • rapid pulse
  • low blood pressure
  • sweating
  • fever
  • weakness in the face, arms, or legs

Common Underlying Causes of Decreased Consciousness

Drugs, alcohol, substance abuse, drug overdose, certain medications, epilepsy, low blood sugar, stroke, and lack of oxygen to the brain are common causes of decreased consciousness.

Other underlying causes of decreased consciousness include:

  • cerebral hemorrhage
  • dementia (Alzheimer’s)
  • head trauma
  • heart disease
  • heat stroke
  • liver disease
  • uremia (end stage kidney failure)
  • shock

What to Expect When You See the Doctor

Diagnosis and treatment of decreased consciousness begins with a complete medical history and physical examination, which includes a detailed neurological evaluation. Medical personnel will want to know about any medical problems you have (such as diabetes, epilepsy, or depression), and any medications you are taking (such as insulin or anticonvulsants). They will also ask if you have a history of abusing illegal or prescription drugs or alcohol.

In addition to your complete history and physical, the doctor may order the following tests:

  • CBC (complete blood count): a low hemoglobin level indicates anemia and an elevated white blood cell count indicates infections, such as meningitis or pneumonia
  • toxicology screen to detect the presence and levels of medications, illegal drugs and poisons in your system
  • electrolyte panel to measure levels of sodium, potassium, chloride, and bicarbonate
  • liver function tests to measure the health of your liver
  • EEG (electroencephalogram): a noninvasive test that uses scalp electrodes to evaluate brain activity
  • EKG (electrocardiogram): a non-invasive test that evaluates heart rate, rhythm, and health
  • chest X-ray to evaluates the heart and lungs
  • CAT scan of the head: a noninvasive test that uses X-rays to make high-resolution images of the brain
  • MRI of the head: a noninvasive test that uses nuclear magnetic resonance to make high-resolution images of the brain.

Treatment for decreased consciousness depends upon its underlying cause. Your outlook worsens the longer you spend less than fully consciousness.

Content licensed from:

Written by: Verneda Lights
Medically reviewed : George Krucik, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.
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