New Research Shows How Brain ‘Wakes Up’ From Anesthesia

Surgical Team Working In Operating roomIf you’ve ever had surgery that required anesthesia, you know the process of waking up can be a jarring one. Anesthesia induces a deep state of unconsciousness in a matter of seconds, but it can take several hours to return to normal after waking. Many people experience confusion, sleepiness, and even delirium-induced hallucinations as they awaken from surgery, but research on this waking process is limited. New research points to a complicated, meandering process through which the brain wakes up from anesthesia.

How Anesthesia Works

The state induced by anesthesia looks a lot like a deep sleep, but it’s actually quite different. Doctors rely on a variety of chemicals to induce unconsciousness, and each works slightly differently in the brain. What all general anesthesia recipes have in common is that they induce unconsciousness while preserving the body’s automatic functions, such as breathing and digestion. Anesthesia also reduces sensitivity to pain, which is why people don’t typically have dreams of being in surgery or experiencing pain when they’re under the knife.

Because a wiggly patient can quickly be injured, anesthesia also limits or eliminates your ability to move. For the one to two people out of 1,000 who briefly awaken during surgery, this paralysis can be terrifying. Fortunately, people who awake during surgery don’t typically experience pain.

Waking from Anesthesia

Doctors have traditionally theorized that, as anesthesia is eliminated from the body, the brain’s electrical activity steadily increases until the brain returns to normal. But new research at Rockefeller University has found that the process of waking up is much more complex.

Researchers knocked rats out using a popular anesthesia called Isoflurane. As the rats awakened from the anesthesia, researchers examined electrical activity in areas of the brain believed to be associated with wakefulness. In fully awake brains, the electrical activity in neurons oscillates, but in an anesthetized or sleeping brain, electrical activity is slower.

Instead of finding a gradual increase in oscillating neurons, researchers found that oscillations occurred suddenly. While every rat’s brain eventually had oscillations in the same “hubs,” the process through which neurons became more active in each hub varied from rat to rat. Researchers believe this indicates that there’s not a single path through which the brain awakens from anesthesia. Because every rat’s brain ultimately used the same hubs, though, the research suggests that certain brain activity is a necessary prerequisite to consciousness.

While research on rats isn’t always applicable to humans, rats and humans respond in similar ways to anesthesia. While anesthesia is extremely safe, a small number of people who undergo surgery don’t wake up. Among people over the age of 65, the risk is higher, with one study reporting an anesthesia death rate of 1 in 10. By gaining a better understanding of how the brain wakes up from anesthesia, researchers may eventually find a way to reduce the risks of undergoing surgery.


  1. General anesthesia. (2013, January 19). Retrieved from
  2. To recover consciousness, brain activity passes through newly detected states. (2014, June 9). Retrieved from
  3. (2011, August 4). Under the knife: Study shows rising death rates from general anesthesia. Retrieved from

© Copyright 2014 All rights reserved.

The preceding article was solely written by the author named above. Any views and opinions expressed are not necessarily shared by Questions or concerns about the preceding article can be directed to the author or posted as a comment below.

  • Leave a Comment
  • Stacie

    June 11th, 2014 at 12:53 PM

    Finding answers to questions such as this would go a long way I believe in helping people be more comfortable when they have to have surgeyr of any kind. I think that alot of us are scared not because of what is being done to us but because there is this fear of never waking up and seeing family again. I think that if there was better understanding for the lay person about what really happens when you are out and the process of waking back up in general, this would lead most of us to a better understanding about what is going to happen and how it really is not that dangerous to undergo the procedure if we are otherwise on good health.

  • Linsey

    June 12th, 2014 at 4:26 AM

    If I don’t have to go to sleep for surgery, believe me, this is not something that I would ever choose!

  • Amelia

    June 23rd, 2014 at 9:12 PM

    So you would rather be awake for surgery?

  • morgan

    June 14th, 2014 at 5:35 AM

    I am not sure that this will change the way that anesthesiologists operate but it should definitely give them more insight and information about what they do.

  • Amelia

    June 23rd, 2014 at 9:10 PM

    Anesthesiologists operate?

  • Nan

    June 17th, 2014 at 3:43 PM

    I had that experience of waking up during surgery once but luckily they realized it right away and put me back under. It almost felt like a drean state but I could hear everything going on around me, but did feel no pain.

  • Amelia

    June 23rd, 2014 at 9:08 PM

    So you were in a “drean” state. Then waked up. Then they asleepened you again?

  • Cynthia

    April 12th, 2015 at 12:09 PM

    My uncle went in for a colonoscopy on friday afterwards they could not wake him up. It has been three days and he is not awake and has a tube breathing for him. Can anyone tell me what is next for him? His children, grandchildren,siblings etc are all at the hosptial so I don’t want to go up there or keep calling but I am so worried.

Leave a Comment

By commenting you acknowledge acceptance of's Terms and Conditions of Use.

2 Z k A



* Indicates required field

Therapist   Treatment Center

Advanced Search

Search Our Blog

Title   Content   Author

Recent Comments

  • The Team: Thank you for your comment, Lucy. We wanted to provide links to some resources that may be relevant to you here. We have...
  • Andrea: Ali, your husbands behaviour is definitely not just autism. I am an autistic myself and have studied cluster B personality disorders in...
  • Lucy: I can relate with all the comments that I am reading, from childhood until present, I have been told that I am lazy, and I will never achieve...
  • Bex: I am confused, my husbands been lying to me about money he has been known to do prescription pain pills in the past and has lied to mw seceral...
  • Jdhers: Interesting read, truthful information. It also leads me to realize I am screwed and will never be able to create a lasting relationship.... is not intended to be a substitute for professional advice, diagnosis, medical treatment, or therapy. Always seek the advice of your physician or qualified mental health provider with any questions you may have regarding any mental health symptom or medical condition. Never disregard professional psychological or medical advice nor delay in seeking professional advice or treatment because of something you have read on