Healthy Living

Do You Suffer from Somnolence?

Drowsiness: Causes, Symptoms and Diagnosis

What is somnolence?

Somnolence is also referred to as sleepiness or drowsiness. It is a state of having a strong desire to sleep or sleeping for unusually long periods of time. The term somnolence comes from the Latin word somnus, which means sleep. Somnolence can be accompanied by signs of lethargy, a lack of mental agility, and feeling weak or too tired. Most of the time, somnolence is regarded as a symptom instead of a medical disorder. 

Somnolence or sleepiness can at times prove to be very dangerous when a person is performing tasks that require focus, such as driving a vehicle or operating heavy machinery. When an individual is too tired or sleepy, there can be chances that he or she may experience microsleeps.


  • Falling Asleep: This is the first sign of somnolence, wherein an individual feels sleepy while watching TV, talking to somebody, sitting in public places, such as meetings, classroom, or movie theatre.
  • Fatigue: An individual would feel lethargic along with a lack of energy. These symptoms are then accompanied by a lack of motivation or interest in carrying out any type of activity. Fatigue is may be due to stress or loss of sleep. Fatigue can also be an early indication of a serious medical condition.
  • Yawning Constantly: Yawning is an involuntary process, which can be triggered by fatigue or drowsiness. 
  • Drowsy Driving: Drowsy driving is a high-risk combination of driving, fatigue, and sleepiness. Drowsy driving usually happens when drivers are sleep-deprived. However, it can also happen in people with untreated sleep disorders, those who are intoxicated with alcohol, taking certain medications, or shift work. 
  • Headache: Headaches can be related to depression and other medical conditions. Sometimes, pain may extend to the neck, jaw, and shoulders.
  • Changes in Weight or Appetite: When an individual suffers from somnolence or drowsiness, then they may tend to overeat or completely stop eating. Individuals who are deprived of sleep tend to overeat at times, thereby leading to weight gain and other health issues.

When to Seek Immediate Medical Help

You should seek immediate medical attention if feel drowsy after:

  • Taking a new medication
  • A drug overdose
  • Experiencing a head injury
  • Being exposed to cold temperatures


There are a number of things that can lead to the occurrence of somnolence. These causes can range from people's lifestyle choices to their mental state. Below are some of the causes of somnolence:

1. Circadian Rhythm Sleep Disorders (CRSD)

The circadian rhythm is also called as the biological clock, and any disorder in this biological clock can be a common cause of sleepiness or drowsiness like in the case of sleep apnea, narcolepsy, or insomnia. Body clock disorders can be intrinsic (advanced sleep phase disorder, delayed sleep phase disorder, non-24-hour sleep-wake disorder, and irregular sleep-wake rhythm) or extrinsic (shift work sleep disorder). 

  • Delayed sleep phase disorder or DSPD - This is mostly related to a faulty timing of sleep, a certain peak time of alertness, the core body temperature rhythm, hormones, as well as other daily cycles. It is often misdiagnosed as insomnia.
  • Irregular sleep-wake rhythm - This relates to carrying out a number of short or long naps in the entire day or a period of 24 hours. 
  • Advanced sleep phase disorder or ASPDThis is a condition in which the patients tend to feel very sleepy and would go to bed quite early in the evening, thereby waking up in the morning quite early as well.
  • Non-24-hour sleep-wake disorder - It is a disorder wherein there is a chronic and consistent pattern of daily sleep onset and wake time delays.

2. Medical Conditions 

Infections may also cause sleepiness. Some theories suggest that somnolence occurs during illnesses to conserve the body's energy while it fights off infections through fever and other methods. 

Other causes of somnolence may include:

3. Medications

There are certain medications that can lead to somnolence or drowsiness. They include:

  • Analgesics – Opioid analgesics such as heroin or oxycodone (OxyContin)
  • Antihistamines – Doxylamine (Unisom-2) and diphenhydramine (Benadryl
  • Antidepressants – Sedating tricyclic antidepressants and mirtazapine (Remeron). Somnolence is uncommon in people who are taking MAOIs, SNRIs, or SSRIs.
  • Antipsychotics – Olanzapine (Zyprexa), thioridazine, risperidone (Risperdal), quetiapine (Seroquel), and ziprasidone (Geodon) except for haloperidol (Haldol)
  • Dopamine Agonists  These medications are used for the treatment of Parkinson's disease (pergolide, pramipexole, and ropinirole)
  • Anticonvulsants – Phenytoin (Dilantin), carbamazepine (Tegretol), pregabalin (Lyrica), or gabapentin (Neurontin)
  • Tranquilizers or Hypnotics – Zopiclone (Imovane, Zimovane), benzodiazepines such as nitrazepam (Mogadon), diazepam (Valium), and barbiturates, such as secobarbital (Seconal) or amobarbital (Amytal) 
  • Antihypertensive Drugs – Amlodipine (Norvasc)
  • Anti-HIV Drugs – Efavirenz (Sustiva)
  • Others  Medications that affect the central nervous system

4. Lifestyle

Increased sleepiness may be due to certain lifestyle choices of people, such as working for an extended number of hours or working on night shifts or rotating shifts. However, when the body adapts to the new schedule, drowsiness usually subsides in most cases. 

5. Mental State

An individual's psychological and emotional state can also influence drowsiness. High levels of anxiety, stress, or depression can significantly increase sleepiness. Another common cause of sleepiness is boredom. If you experience any of the mentioned mental conditions, you are also more prone to feeling unmotivated or fatigued. 


The treatment of somnolence usually depends on its exact cause.


If the cause of drowsiness is physical fatigue or stress, it can be simply treated at home by getting plenty of rest, including setting certain distractions. You could also try identifying the main cause of your drowsiness along with taking some necessary steps to appropriately resolve the issue. 

Medical Care

The doctor usually tries to identify the main cause of drowsiness through asking about the patient's symptoms. The doctor may ask questions that are related to:

  • Sleeping habits
  • Regular amount of sleep 
  • Snoring habits
  • Frequency of falling asleep or feeling drowsy during the day

The doctor may refer the patient to a therapist or counselor if a psychological issue is suspected. When drowsiness is caused by certain medications, the doctor may prescribe an alternative medication or alter the drug's dosage to avoid drowsiness. Do not stop taking prescription medications unless otherwise instructed by the doctor. 

Certain tests may also be carried out to identify the cause of your drowsiness. Most of these tests are painless and noninvasive. The tests may include any of the following:

If restless legs syndrome (RLS), obstructive sleep apnea, and other sleep disorders are suspected, the doctor may recommend a sleep study test. In a sleep study, patients are required to spend the night in the hospital or sleep center under the supervision of a sleep specialist. During the test, a patient's body movements, blood pressure, heart rhythm, oxygenation, breathing, as well as brain waves are closely monitored to detect any signs of sleep disorders. 


Drowsiness can be prevented by having a consistent and regular amount of sleep every night. To feel recharged and refreshed, most adults approximately need eight hours of sleep. However, some individuals may need more sleep, particularly those who have an active lifestyle and those who have certain medical conditions. 

If you are still experiencing persistent sleepiness along with signs of depression, mood changes, or uncontrollable feelings of anxiety and stress, immediately consult a doctor to properly diagnose and treat your condition.