Knocking off sleep – a complicated relationship between sleep and concussion

Let me begin by stating that I’m not a sleep specialist, and this blog is not a piece of medical advice. What fascinates me the most about sleep is how this state of apparent inactivity holds such sway in our lives. My series The Sleeptime tries to capture the essence of the inquisitiveness that  I have had for a long time and being a neuroscientist now, I try to delve deeper. Today’s blog is set in the backdrop of a childhood experience that has etched a sense of fear regarding falling and sleep.

This experience did not stem from any nightmare, which can be a story for another day, but was something very real. For now, let us travel back to my 6th-grade summer vacation. This was the first time my parents had entrusted me with babysitting my sister. She was 6 months old then — a jolly baby who had recently discovered the thrill of rolling over and attempting to thrust herself forward on her belly in a bid to explore the brave new world. I was extremely excited to have been given the role of a big responsible sister, and I was prepared to take care of her with all enthusiasm.

The first couple of hours were great! I innovated all sorts of games to keep her occupied. However, as time passed, I started feeling exhausted and found it a little difficult to keep with her boundless energy. So, I devised a way to restrict her movement and conserve some of my own energy. The plan was straight forward; I will feed her (as fat babies don’t move much 😉, at least that what I thought), place her on my parents’ high-rise bed, and build a wall of pillows all around her. The success was immediately rewarding- as I relished her failed attempts to climb up the fortification. I was finally rest assured that the victory was mine as I saw her surrendering to sleep. Basking in my own glory, I plugged my headphones on and oblivious to my surroundings, kicked off to play Road Rash.

By now, you must have guessed how this story ends. My sister woke up fresh and even more energetic thanks to the food and the short nap. She re-attempted the cross over and unfortunately, this time was successful. She crashed head first on the floor and suffered a significant concussion, which I realized only after 15 minutes at the end of my triumphant lap. Perplexed by what just happened and terrified by her constant vomiting, I decided to call my neighbor for help. The whole journey to the hospital was a haze for me, but only one statement from my neighbor kept on echoing ‘Do not let her fall asleep, it’s deadly’. Despite my best efforts, I couldn’t keep her awake, and in addition to the concussion, she suffered extreme fatigue on our way to the hospital. Rest of the drama is history, but all is well that ends well as today she is a healthy and vibrant young woman. Nonetheless, this accident still haunts me, and I often wonder about the origin of the notion that dozing off post head injury is detrimental for the patient?

The neuroscience argues (1,2,3) that this could be a myth, and in fact, rest is recommended in the acute stage, immediately following injury – up to 24 to 48 hours – before guided, a gradual return to activity. The longstanding fear was that one wouldn’t wake up if they slept following a concussion. This notion developed due to a misunderstanding of medical terms called ‘’lucid interval’’. In medicine, lucid interval refers to a short time window where the patient wakes up from being unconscious and temporarily everything seems to be improving, but after which the condition deteriorates. A lucid interval, although rare, is especially indicative of an epidural hematoma, where the brain is internally bleeding after a severe head injury. An estimated 20-50% of patients with epidural hematoma experience such a lucid interval, which is a large scary number but not the complete picture.

Sleeping through night after concussion is okay once you receive the green light from your physician. Image credit: UPMC

My sister is one of the lucky ones, but the number of people suffering from post-traumatic head injuries is staggering and goes beyond my personal invested interest in this topic. For example, in the USA alone, there are 1.6-3 million traumatic brain injuries each year, and worldwide it is 69 million. The problem intensifies, not just because the patients potentially could slip into a lucid interval, but also because detection of the exact extent of the damage after a concussion is nearly impossible. To establish the severity of the injury most of the physicians rely on the symptoms such as a loss of balance, blurred vision, tingling in the arms or the legs, vomiting, headaches, and confusion. These are indeed critical indicators, but not all patients are the same and might not even show these symptoms. Therefore, reliable early detection is the key that could help all the patients with concussion.

There is some hope for the future. A simple blood test might be able to detect concussion by measuring specific proteins like Ubiquitin C-Terminal Hydrolase-L1 and Glial Fibrillary Acidic Protein in the bloodstream. In 2014 it was discovered by a team at Orlando Regional Medical Centre in Florida that these two proteins are released by the brain when a blow to the head has caused some damage to it. Admittedly, this test will take a few more years to develop, and in the meantime, doctors will have to rely on the observation of symptoms.

If you are with someone who has a concussion or head injury, there are specific guidelines available from several organizations like World Rugby and Britain’s NHS. However, it is essential to get immediate medical care and watch out for symptoms closely. If someone is not confused or vomiting, or has double vision or trouble walking or a severe head or neck ache, these recommendations do not include the advice to keep them awake. In fact, rest is what’s needed, and the brain needs to heal by not doing too much work. Although it should be highlighted here that until very recently, a few trials have tested this advice and it still worries some researchers. The hope is in the future when we will have the outcome of several new trials underway, and we should soon have better information on the best practices to take care of patients with head injuries.

Surely to recover from a concussion, it requires healthy and adequate sleep. Although, for about 30-70% of patients with mild head injuries, it is not easy. There is a palate of different sleep disorders which are more common in the days and weeks following a concussion. This, in turn, can halt the necessary healing process. A period of depression and anxiety may also follow a head injury, as neuronal damage influences mood and behavior and can further worsen sleeping.

Further research connecting concussions and sleep health has revealed even more complex links. One study found that although the concussed group reported more sleep problems than the healthy group, there were no real differences observed during sleep when both the groups were monitored under a brain scan. Instead, they landed up discovering a vicious cycle. The head injury patients produced more delta waves (associated with deep sleep) and fewer alpha waves (associated with relaxed wakefulness). Suggesting that concussion might create more problems with wakefulness than with sleep itself. These disturbances in wakefulness can, in turn, lead to additional fatigue and sleep problems like insomnia. Moreover, patients with repeated concussions, for example, rugby or football players can lead to chronic traumatic encephalopathy, a neurodegenerative disease that can lead to dementia and causes the same sleep problems as a concussion.

Many rugby or football players suffer from chronic traumatic encephalopathy, upon repeated concussions. Image credit: Pixabay

Clearly, concussions can cause both short-term and long-term disturbances. Therefore, it is essential that patients try and get both mental as well as physical rest to assist them on the road to recovery. They can do this effectively by practicing good sleep hygiene habits, turning off electronics and avoiding mentally taxing activities during the day for a while, and, if needed, taking over-the-counter sleep aids under their physician’s supervision.

We publish using the Creative Commons Attribution (CC-BY) license so that users can read, download and reuse text and data for free – provided the authors, illustrators, and the primary sources are given appropriate credit.

Our collaborators on this article

Illustrator: The cover image is made by a science communicator friend, Ipsa Jain. She uses arts and design to start conversations about science. Ipsawonders is one woman labor of love. She wants to create beautiful things that speak science.

Editor: The article is edited by Rashmi Guha Ray, who is a journalist from India. Her undying passion for politics carried her to the western shores to study MA in Conflict, Governance, and Development in the University of York, UK. She is currently working as a research assistant in a project on migration. A trained editor who is hopelessly in love with words, Rashmi loves taking up new challenges in editing and rewriting and the Serendipity Brain is one of her latest ventures.

Sleep-flying is a thing!

I assure you that this blog is not about astral projections, but about the mindblowing discovery on how birds can sleep-fly without bumping into trees. So, here you go! I have given away the suspense. Nonetheless, do read along as I cherish my love for sleeping and long-standing collaboration with Ipsa Jain.

Scientists have found that migratory birds can fly for 200 days straight, eating and sleeping while soaring through the sky. Image credit Ipsawonders

A few years back, I got the chance to visit Sultanpur Bird Sanctuary, India. It is a magical place to be. Every winter, around 250 species of birds and 1 enthusiastic Homo species known as Bird watchers confluence in the park. Both playing one’s cards close to their chest; displaying their magnificence, skills and power.

Then there is me fighting off my early morning slumber, and continuously bickering about how long can it possibly take to reach the park through the infamous Delhi-NCR traffic. However, the serenity of this place has something, that allowed me to think about how these nomadic birds sleep while migrating all the way from Siberia, Russia, Turkey, and Eastern Europe.

Alas! I’m not the only one who comes up with such fantastic thoughts. For years, scientists have been suspicious that birds could sleep mid-flight, as several bird species can fly non-stop for weeks. On the other hand, some researchers propose that few birds can forgo sleep entirely while flying for extended periods of up to 200 days straight.

This time scale will lable a human insane, even if s(he) contemplates trying it out, Isn’t it? Humans along with many other species would experience irritability, hallucination, cognitive impairments, paranoia, and psychosis as side effects of sleep deprivation within 3 days or less.

So what makes birds’ brain so special?

Due to the lack of studies monitoring the sleep patterns of flying birds, the above hypotheses had previously been uncharted. Ratthenborg and his team in 2016, were among the first ones to pursue this question as they embarked on a red-eye flight to the Galápagos Islands; monitoring the brain activity of great frigatebirds (Fregata minor).

The great frigatebird is a fascinating model to study these questions as this species of large seabirds can spend weeks continuously flying over the ocean in search for food and shelter, and to my surprise without bumping into obstacles on its way. The team’s work provided evidence that birds do indeed sleep while flying.

The great frigatebird (Fregata minor) is a large seabird in the frigatebird family. Their nesting populations are located in the tropical Pacific (including the Galapagos Islands) and Indian Oceans, as well as a small population exist in the South Atlantic. Image credit Charles J Sharp

How do they know that?

The team attached a lightweight, portable device onto the heads of frigatebirds, to track the brain activity. Their equipment used electroencephalography (EEG) to identify if and when the birds were asleep during the flight. After 10 days of non-stop flight, the birds returned to land, and the researchers recollected the devices to observe the results.

The team showed that flying frigatebirds display unihemispheric slow wave sleep (USWS). It is a unique capability of the brain, that allows the animals to doze off one hemisphere of the brain at a time. This way is allowing them to watch out for potential threats and roadblock through one open eye.

Other animals and birds are also equipped with such a superpower. For example, the Dolphins have been observed to exhibit USWS, letting them sleep while swimming. Also, on land, the Mallard ducks (Anas platyrhynchos) keep one cerebral hemisphere up and running letting the corresponding eye open, directed away from the fellow flock-mates, but toward potential threats. This way it has devised a safety net out of the use of USWS, when sleeping at the edge of their group.

The Mallard (Anas platyrhynchos) is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa. Image credit momentofscience

If now you are thinking that this is the coolest part, wait for it.

Rattenborg and his colleague also found that frigatebirds continue to fly even when both the cerebral hemispheres are asleep, that means both the eyes are entirely closed. For simplicity sake, imagine it as some sort of autopilot mode. The monitored birds in this study, even experienced brief bouts of rapid eye movement (REM) sleep, although they lasted only a few seconds. They observed that during deep REM sleep birds head droops due to relaxed muscle tone, although this did not affect the flight pattern. Suggesting that the frigatebirds did sleep for brief periods in mid-flight (~ 42 min per day), they spent a majority of the flight awake and half-brain awake.

Admittedly, it still remains unclear how birds have adapted to function with such little amount of sleep. Nevertheless it opens up other questions like, why us and many other animals suffer consequences of sleep deprivation dramatically.

The cover image is made by a science communicator friend, Ipsa Jain. She uses arts and design to start conversations about science. Ipsawonders is one woman labor of love. She wants to create beautiful things that speak science

We publish using the Creative Commons Attribution (CC-BY) license so that users can read, download and reuse text and data for free – provided the authors, illustrators, and the primary sources are given appropriate credit.

How can some lucky ones sleep like a log around a bulldozer?

Well guilty as charged! I’m indeed one of those ‘lucky’ ones that you all envy. I can sleep through almost any din and bustle and wake up fresh as a daisy the next morning. Nothing, other than sudden hunger pangs at odd hours, can disturb my otherwise seamless slumber. The only exception was the night before my Ph.D. defense when I was woken up by a panic attack, and in my three decades of existence, that was probably the only time it happened. My reputation precedes me, and I’m referred to as Kumbhakarna in my close circle.

Yes; bless the man who first invented sleep…..
John Godfrey Saxe (1816–1887);

My sister, sadly, is exactly the opposite! The rustling of bedsheets, the softest tap on the door or the gentlest of breeze are enough to wake her up. She struggles to remain asleep while I snore away to glory in that very room, blissfully unaware of the mundane world around me. But what is it that makes me so impervious to noise? Is my brain wired differently and so responds (or doesn’t) to sound in peculiar ways?

I may not be reacting to sounds around me while I sleep, but the brain is always listening. It continues to register and process sound on a basic level, even when we are sound asleep. It’s actually good, because even though we may not react to all sorts of noise, a firm alarm wakes us up with a jolt.

One of the methods to understand our brain during sleep is electroencephalogram (EEG). It records the ‘brain waves’ which are nothing but the synchronized bouts of electrical activities from masses of neurons talking to each other either to execute a task or not do anything at all. To register these activities, scientists place electrode patches on the scalp of a sleeping person and record, especially from the brain’s thalamocortical system. As we progress through the different stages of sleep, our brain produces different types of brain waves. Every rise, fall, and jitter of these waves tell us a different story about our thoughts, emotions, and behaviors.

How much noise can disturb our sleep depends on several factors like which stage of sleep we are in. That is the reason why it is more probable that noises will wake us up from light sleep, rather than from deep sleep.

EEG Recording. Lumen Learning

Interestingly, a study led by Thanh Dang-Vu and Ellenbogen found that for “sound sleepers”, specific brain waves may make them more tolerant to noise.

They did a tad bit mean experiment on healthy volunteers in their sleep laboratory for three nights. On the first night, participants could sleep blissfully in their comfy beds. However, for the next two consecutive nights, the researchers placed a speaker behind the beds and played everyday noises, such as alarm clocks or toilets flushing, at varying volumes and noted how loud noise had to be before arousing each person. All these nights Thanh Dang-Vu and team kept recording the brain waves.

They showed that brain activity in the face of noise is controlled by specific brain waves during sleep. In particular, waves called sleep ‘spindles’ prevent the transmission of sounds to auditory brain regions. In contrast, when sounds were associated with brain waves called ‘K-complexes‘, activation of auditory areas was larger, and individuals were prone to waking up.

Those with higher spindle rates on the quiet
night were more stable sleepers on the noisier nights. Wikipedia

In another study, Thanh Dang-Vu resorted to using EEG in combination with functional magnetic resonance (fMRI) imaging on 19 healthy individuals. The idea was to not just monitor the brain waves, but also to visualize which brain areas light up in response to sound during sleep. Here, he and his colleagues found that sound, when the person is awake, activates two main brain regions thalamus and primary auditory cortex. These responses persist during deep NREM sleep, except throughout spindles, during which they became less consistent. When sounds elicited a K complex, the activity in the auditory cortex was enhanced.

“Laugh and the world laughs with you, snore and you sleep alone.” – Anthony Burgess;

So, it could be that those who are blessed with more sleep spindles and/or less K-complex, could sleep even in a loud environment. However, during sleep, our brain produces both K-complexes and sleep spindles, depending on the stage of sleep. Therefore, our perception of the environment is not continuously reduced, it rather varies throughout during sleep.

Several other factors may make our brain respond to sound in certain ways as well. Like the time of the day when we go to sleep and even how we associate with specific sound itself. That’s plausibly why a parent can sleep soundly through their partner’s snoring but wakes up immediately when their baby cries at night.

So, the next time you lie tossing and turning in bed thanks to your teenage neighbour’s blaring stereo, you know who to blame for your ordeal.


This article is edited by Rashmi Guha Ray. She is a journalist from India whose undying passion for politics carried her to the western shores to study MA in Conflict, Governance, and Development in the University of York, UK. She is currently working as a research assistant in a project on migration. A trained editor who is hopelessly in love with words, Rashmi loves taking up new challenges in editing and rewriting. 


We publish using the Creative Commons Attribution (CC-BY) license so that users can read, download and reuse text and data for free – provided the authors, illustrators, and the primary sources are given appropriate credit.