What Causes Insomnia? by Dan Kwartler (Transcript)

TED-Ed Lesson:

What keeps you up at night? Pondering deep questions? Excitement about a big trip?

Or is it stress about unfinished work, an upcoming test, or a dreaded family gathering?

For many people, this stress is temporary, as its cause is quickly resolved.

But what if the very thing keeping you awake was stress about losing sleep?

This seemingly unsolvable loop is at the heart of insomnia, the world’s most common sleep disorder.

Almost anything can cause the occasional restless night – a snoring partner, physical pain, or emotional distress.

And extreme sleep deprivation like jetlag can throw off your biological clock, wreaking havoc on your sleep schedule.

But in most cases, sleep deprivation is short-term. Eventually, exhaustion catches up with all of us.

However, some long-term conditions like respiratory disorders, gastrointestinal problems, and many others can overpower fatigue.

And as sleepless nights pile up, the bedroom can start to carry associations of restless nights wracked with anxiety.

Come bedtime, insomniacs are stressed. So stressed their brains hijack the stress response system, flooding the body with fight-flight-or-freeze chemicals.

Cortisol and adrenocorticotropic hormones course through the bloodstream, increasing heart rate and blood pressure, and jolting the body into hyperarousal. In this condition, the brain is hunting for potential threats, making it impossible to ignore any slight discomfort or nighttime noise.

And when insomniacs finally do fall asleep, the quality of their rest is compromised. Our brain’s primary source of energy is cerebral glucose, and in healthy sleep, our metabolism slows to conserve this glucose for waking hours.

But PET studies show the adrenaline that prevents sleep for insomniacs also speeds up their metabolisms. While they sleep, their bodies are working overtime, burning through the brain’s supply of energy-giving glucose.

This symptom of poor sleep leaves insomniacs waking in a state of exhaustion, confusion, and stress, which starts the process all over again.

When these cycles of stress and restlessness last several months, they’re diagnosed as chronic insomnia.

And while insomnia rarely leads to death, its chemical mechanisms are similar to anxiety attacks found in those experiencing depression and anxiety. So suffering from any one of these conditions increases your risk of experiencing the other two.