What is Twilight anesthesia?

What is Twilight anesthesia

Twilight anesthesia, also known as conscious sedation, is a type of anesthesia that induces a state of relaxation and drowsiness while allowing you to remain conscious and responsive. It is often used for certain medical or dental procedures.

You may have limited memory of the procedure due to depressed consciousness, however, you will be able to respond to painful impulses during the procedure. Moreover, your vital functions such as breathing and cardiovascular stability are typically maintained.

It is given for minor surgical procedures such as x-rays, endoscopy, dental and emergency procedures.

What do you experience after twilight sedation? 

You will experience varying depths of sedation after the drug administration depending on the dosage and given medicine, procedure requirements, and your mental health. 

  • Minimal sedation keeps you awake but relaxed and able to interact.
  • Moderate sedation depresses consciousness, but you will respond to verbal instructions or react to touch. Breathing remains unaffected during the procedure. 
  • Deep sedation takes you into a state of mind where it is difficult to stay awake, but you will respond to repeated or painful stimuli. 
  • Dissociative sedation puts you into a trance-like cataleptic state, where you become detached from reality and feel everything around you is unreal. You become unaware of the pain and retain no memory of the procedure. Still, you can follow the requests given to you. Furthermore, your breathing and reflexes remain intact.

Who can get twilight anesthesia?

Twilight sleep anesthesia is given in patients with 

  • Fear of treatment 
  • Prolonged and painful procedure that can leave painful memories
  • Health conditions that can aggravate from trauma of catching the sight of the surgical procedure, such as asthma, heart disease, and epilepsy.
  • Mentally challenged individuals
  • Ineffective anesthesia due to specific reasons.
  • An uncooperative child or anxious adult.

How is twilight anesthesia administered in dentistry?

It is given to a patient in three ways: oral, intravenous (into the blood), and inhalation. 

Inhalation anesthesia 

Nitrous oxide (NO) is most frequently used in dentistry to calm dowm an uncooperative child and anxious adult. A mixture of NO and oxygen is used as a sedative. It calms the nerves and decreases pain perception without affecting your breathing. A low concentration of NO with oxygen is used for conscious sedation, as higher levels lead to loss of consciousness.

Most NO-oxygen delivery systems are set to deliver a maximum of 70% NO and 30% oxygen to sedate the patient. Moreover, the oxygen concentration delivered during NO inhalation is 9% more than naturally in the air.

The NO delivery system is an oxygen fail-safe device that stops the flow of NO when the flow of oxygen is stopped. NO has low tissue solubility, making the sedation and recovery rate faster. It keeps you awake and responsive, keeping all reflexes intact. It can’t be given if you have lung-related conditions like flu, porphyria, and COPD. 

IV sedation 

Intravenous sedation is given into the veins and is less commonly used in dentistry. The injections are deposited behind the last molar. The drugs have high tissue solubility with rapid onset of action. The sedative dosage doesn’t decrease the pain perception, so an additional local anesthetic is added to make the procedure painless. IV sedation doesn’t affect the respiration or blood pressure. 

IV Twilight sedation drugs: Diazepam, midazolam, ketamine, fentanyl, and propofol are some of the few drugs used for IV sedation. 

Oral sedation 

Oral sedation is also frequently used to sedate patients seeking dental treatment—a tablet of sedative is given 1 hour before the procedure. For children, the tablet is dissolved in a sweet drink and given to the child 20 minutes before surgery. 

Oral twilight sedation drugs: The dentist often prescribes Halcion (triazolam), Valium, Xanax, or Ativan for a 1-2 hour long dental procedure, for instance, surgical wisdom tooth removal or root canal treatment.  

Can you talk during twilight sedation? 

Yes, you can understand and respond to the instructions, but the twilight anesthesia depresses your consciousness, so you can’t have a long and meaningful discussion. 

It is recomeneded not to drive or operate heavy machinery for 24 hours after the procedure. You also require someone to accompany you to home after the procedure.

What is death rate in twilight anesthesia?

Twilight sedation is a relatively safe procedure associated with little to no side effects in healthy patients. However, the risk of severe adverse effects and death is directly proportional to the severity of the preexisting medical condition. 

According to research, the 30-day mortality rate during Transcatheter Aortic Valve replacement in patients treated with conscious sedation was 2.9% and 4.9% in patients with general anesthesia. 

Can you feel pain during twilight anesthesia? 

Inhalation anesthesia doesn’t cause any pain as it is delievered through a mask. However, IV injection may cause pain in some patients.

Is twilight anesthesia safer than general anesthesia?

Yes, twilight anesthesia is much safer than general anesthesia. The following are differences and why twilight anesthesia is safer than general anesthesia:

Twilight anesthesia vs. general anesthesia: General anesthesia (GA) is usually reserved for major and complex surgeries involving extensive tissue cutting. It is given into the blood with an injection, and patients lose consciousness after it. It also depresses your respiration and heart rate. GA requires a higher dose or more potent medicine and is linked to increased side effects than twilight anesthesia. The recovery takes longer and requires up to 24 hours to completely recover. 

On the other hand, twilight sedation makes you drowsy but keeps you awake with intact reflexes. A lower dose of medicine is required to get the desired effect, so it is associated with fewer side effects. It can be given through inhalation, oral (tablets), and intravenous routes. The recovery ranges from few minutes to 24 hours, depending upon the method of administration. Moreoever, twilight anesthesia is reserved for minor surgeries in anxious and uncooperative patients.   

What are the side effects of twilight anesthesia?

Intravenous injections are more associated with side effects. Headache, drowsiness, nausea, and vomiting are the most frequent side effects of twilight anesthesia and may last several hours after the procedure. 

A few IV sedatives (ketamine) increases saliva production and mucous secretion from the respiratory tract and may require saliva-reducing drugs before the treatment.

The dosage required for sedation is low, so the risk and side effects are less frequently seen. However, the sedative may slow your breathing, requiring oxygen. The nurse will immediately give you oxygen when your oxygen levels drop, or you experience shortness of breath. 

In fewer cases, sedatives may lower your blood pressure. You will get IV fluids if there is a marked decrease in blood pressure.   

These side effects often occur if you take any medicine that interacts with the given sedative, so it is critical to inform your doctor or dentist about your medical and drug history to avoid undesirable consequences. 

Is twilight anesthesia safe?

Yes, it’s a safe procedure for healthy patients and patients with mild health conditions. Patients with multiple co-morbidities and drugs are at risk of adverse effects. Therefore, it is vital to inform your healthcare provider about your health status and the medications.

Several blood pressure-lowering medications, anticonvulsants, steroids, antibiotics, etc., interact with sedatives. Long-term intake of prescribed drugs to manage your health condition may inhibit or activate selective liver enzymes. This can amplify or decrease the effect of the sedative or other prescribed medications, worsening your health condition. 

Your drug history will help your healthcare provider select the proper sedative and dosage or if it is needed to stop or change the prescribed drug for the surgery. 

How long does twilight anesthesia last?

The twilight anesthesia recovery time depends upon the method of adminstration. NO oxide keeps you drowsy and quickly reverses the effect once its supply is discontinued. Oral and IV sedation may take 24 -36 hours to recover completely. 


Twilight anesthesia is a sedation to calm the nerves and decrease your pain perception. It makes you drowsy, however, you are able to respond to verbal requests and touch sensations. Moreover, it allows you to comfortably tolerate the procedure without affecting blood pressure and breathing. 

You may not remember the procedure, but your vital functions such as breathing and cardiovascular stability are typically maintained.

Twilight anesthesia is considered safer than general anesthesia, but provides a deeper level of sedation than local anesthesia alone. The specific drugs and techniques used can vary based on the medical professional and the nature of the procedure.

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