Decreased alertness is a state of reduced awareness and is often a serious condition.
A coma is the most severe state of decreased alertness in which a person cannot be awakened or interact with their environment. A long-term coma may shift into a vegetative state.
Many conditions can cause decreased alertness, including:
Extreme tiredness or lack of sleep
or
High or low blood sodium concentration
Infection that is severe or involves the brain
Thyroid conditions that cause
or
very high thyroid hormone levels
Brain disorders or injury, such as:
or
(advanced cases)
Head trauma (moderate to severe cases)
(usually when the stroke is either massive or has destroyed certain areas of the brain such as the brainstem or thalamus)
Infections that affect the brain, such as
or
Injury or accidents, such as:
Diving accidents and near drowning
Very low body temperature (
)
Heart or breathing problems, such as:
Abnormal heart rhythm
Lack of oxygen from any cause
Severe
Severe lung diseases
Very
Toxins and drugs, such as:
Alcohol use (binge drinking or damage from long-term alcohol use)
Exposure to heavy metals, hydrocarbons, or toxic gases
Overuse of drugs such as opiates, narcotics, sedatives, and anti-anxiety or seizure medicines
Side effect of almost any medicine, such as those used to treat seizures, depression,
, and other illnesses
Get medical help for any decrease in consciousness, even when it is due to alcohol intoxication,
, or a seizure disorder that has already been diagnosed.
People with epilepsy or other seizure disorders should wear a medical ID bracelet or necklace describing their condition. They should avoid situations that have triggered a seizure in the past.
Get medical help if someone has decreased alertness that cannot be explained. Call 911 or the local emergency number if normal alertness does not return quickly.
Most often, a person with decreased consciousness will be evaluated in an emergency room.
The health care provider will perform a
. The exam will include a detailed look at the heart, breathing, and nervous system.
The health care team will ask questions about the person's medical history and symptoms, including:
Time pattern
When did the decreased alertness happen?
How long did it last?
Has it ever happened before? If so, how many times?
Did the person behave the same way during past episodes?
Medical history
Does the person have epilepsy or a seizure disorder?
Does the person have
?
Has the person been sleeping well?
Has there been a recent head injury?
Other
What medicines does the person take?
Does the person use alcohol or illicit drugs on a regular basis?
What other symptoms are present?
Tests that may be done include:
(CBC) or
or
of the head
Oxygen level (pulse oximetry or
)
(ECG)
(EEG)
and
Toxicology panel and blood alcohol level
Treatment depends on the cause of the decreased alertness. How well a person does depends on the cause of the condition.
The longer the person has had decreased alertness, the worse the outcome.
Stuporous; Mental status - decreased; Loss of alertness; Decreased consciousness; Changes in consciousness; Obtundation; Coma; Unresponsiveness
Berger JR, Price R. Stupor and coma. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 5.
Greer DM, Bernat JL. Coma, disorders of consciousness, and brain death. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 373.
Lei C, Smith C. Depressed consciousness and coma. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 12.
Updated by: Joseph V. Campellone, MD, Department of Neurology, Cooper Medical School at Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.