Guernica, by Pablo Picasso (1937)

Picasso's "Guernica", painted after warplanes bombed the village during Spain's civil war, depicts the suffering of innocents.

I did not sleep well during the night following the Boston Marathon bombings. It took me a long time to fall asleep, and I woke up early the following day, unable to get back to sleep. This is very unusual for me. Immediately after the explosion, I had been glued to the television, just as confused and disoriented as everybody else. I live two hours away from Boston, but I worried about the people that I know there. Why does witnessing a traumatic event disturb our sleep even when we are not in imminent danger? 

I was practicing medicine in Manitoba, Canada, on 9/11. Like people all over the world, I remember where I was that day. Our staff in the sleep clinic obtained a television, and watched all day as events unfolded. Patients cancelled their appointments that day, but for the next several weeks,  we saw an increase in the number of patients with insomnia referred to our sleep clinic. Winnipeg is 2,000 miles from New York City, yet the impact on sleep in our community was substantial.

In both events, the media repeated the same images over and over again. In the case of 9/11, who can forget the footage of people running as a cloud of smoke resembling a nuclear explosion barreled towards them? Similarly with the Boston Marathon explosions, the media repeatedly broadcast the same images, at times from slightly different angles. The repetition of the images was disturbing, and finally we just turned off the television. One does not need the computer-generated imagery of a horror movie to create terror. The pictures shown on television had a much greater impact because what we were seeing was real.

What controls our sleep?

The brain is controlled by systems that put us to sleep, systems that wake us up and keep us awake, and a biological clock that helps control when we sleep. The main switch that puts us to sleep is located in cells in a part of the hypothalamus called the ventrolateral preoptic nucleus (VLPO). The cells in the VLPO release chemicals including GABA and galanin that inhibit some parts of the brain that wake us up. The parts of the brain that wake us up release chemicals including orexin (which is reduced in narcolepsy), and histamine (as opposed to antihistamines, which may put you to sleep), noradrenaline, and serotonin. The sleep/wake system is complex, but generally works remarkably well.

What happens in our brains when we witness trauma?

I asked a colleague, Robert Stickgold, PhD, a world-renowned expert on sleep and dreaming at Harvard, to address the link between trauma and insomnia. His response:

“Psychological trauma often develops when you are confronted with an experience of threat that feels overwhelming. The mind and body respond with a fight-or-flight rush of adrenalin, and a memory of the event is created in intense detail, tagged as extremely important and unresolved. It is probably this tagging that impacts our sleep (Stickgold & Walker, 2013). One of the greatest achievements of the human brain is its incredible ability to take complex information and figure out what it means — both in the moment and for our future. In the case of traumatic events, this can take a long time.

After September 11th, we all walked around in a daze, feeling that we didn’t understand what had happened. Of course, on the one hand, we understood all too well — large plane loaded with fuel, high speed, tall building. What’s not to understand? But we didn’t understand what it meant for our own futures. I have plane tickets to Amsterdam in two weeks; should I cancel them? I work in a 12-story hospital; should I go to work? The man in front of me getting on the subway has a swarthy complexion and a large backpack; should I turn and run?

More and more research suggests that much of this working-out of the meaning embedded in complex experiences occurs while we sleep (Stickgold, 2010), and during the sleep-onset period, when we’re lying in bed waiting for sleep to engulf us, our mind seems to line up topics for the night’s sleep-dependent memory processing. What didn’t I finish today, what do I need to get done tomorrow, what happened today that I still haven’t figured out? With luck, these just rumble through your mind like a distant freight train in the night. But sometimes they take on the proportions of a train wreck. The deadline for that grant application was this afternoon! I never canceled that appointment! The result can be a rush of adrenalin that makes sleep, at least for the next while, impossible.

The significance for insomnia of "things unfinished" is, I am convinced, huge. I have been writing an application to get my main research grant renewed, and it has been horrific. Last night, at about 3:30AM, I somehow thought of a sentence I wanted to add. I lay there, from 3:30 until after 4:00, literally replaying and rephrasing the sentence over and over, despite all my efforts to relax, clear my mind, count sheep, whatever! Finally, a little after 4AM, I got up, went to my computer, and added the sentence — I was asleep five minutes later. Insomnia is all about not being able to say, "It's over." So is PTSD. 

Sleeping pills and anti-anxiety medications might help prevent this rush of adrenalin, which could be helpful. But if they also take the anxiety-provoking topics off the table for our nightly processing, it could make things worse. I have suggested (Stickgold, 2008) that PTSD develops precisely when this sleep-dependent processing fails, leaving traumatic memories in their original, painfully detailed form, without meaning or understanding. So whether these medications are ultimately helpful or not remains unclear. We know that alcohol can also speed sleep’s onset, but in the end it doesn’t really help anything.”

Stickgold, R. (2008). Sleep-dependent memory processing and EMDR action. Journal of EMDR Practice and Research, 2(4), 289-299.

Stickgold, R. (2010). Memory in sleep and dreams — The construction of meaning. In S. Nalbantian, P. M. Matthews & J. L. McClelland (Eds.), The memory process — Neuroscientific and humanistic perspectives. Cambridge MA: MIT Press.

Stickgold, R., & Walker, M. P. (2013). Sleep-dependent memory triage: evolving generalization through selective processing. Nature Neuroscience, 16(2), 139-145.”



In our personal quest to make sense of the bombings at a non-political, annual public event on a sunny spring day in Boston, millions of people in the United States and around the world lost sleep the night of April 15, 2013. For the vast majority, sleep will return to normal within a few days or weeks as we sort out the reasons why it happened and what it means for our daily lives.  

For some, however, the sleeplessness will continue and some may even develop post-traumatic stress syndrome and awaken because of nightmares triggered by the images they witnessed either in person or on television or the internet. Many of the injured, the witnesses, bystanders, family members, first responders, and caregivers are at risk of developing post-traumatic stress disorder. Insomnia is often the red flag that indicates there is psychological work to be done, and that work sometimes requires professional help.


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