Why do I fall asleep on the couch, but then as soon as I go to bed, I’m wide awake?

You’re dozing off, so you go to bed. But as your head hits the pillow, sleepiness abandons you. It’s frustrating, but it makes perfect sense from an evolutionary perspective.

Over millions of years, our brains have evolved survival mechanisms, shifting between different states of alertness in response to our environment. The upper brain—the prefrontal cortex—is logical and strategic. Your lower brain—the limbic system—is the primitive, emotional center, and if it perceives a threat, it overrides the upper brain to trigger the “fight-or-flight” stress response to help us react to protect ourselves.

For our prehistoric ancestors, sleep was risky, leaving them vulnerable to predators. The human brain therefore developed the habit of performing a last-minute scan of surroundings to ensure it was safe to go to sleep. For modern humans, having trouble sleeping or being startled awake—even once—can lead to a situation where the act of going to bed triggers our survival instincts and readies the body to respond to lurking danger.

SWITCHING OFF THE PRIMAL BRAIN

To overcome your primal instincts, you need to find ways to pacify the limbic system, helping your brain override its natural response to threats and reassure it that there is nothing to fear from going to bed.

• A relaxation exercise, such as the one can help calm the limbic brain’s state of watchfulness.

• Does your bedroom evoke a sense of calm and security? See How do I make my bedroom a sleep sanctuary? and Does the position of my bed affect how well I sleep? for ways to make your sleeping space feel relaxing and safe.

• If you can, avoid situations that might trigger stress, such as difficult conversations with a partner or family member or looking at work emails.

• CBTI or other cognitive strategies, which change how you perceive sleep, can be useful.

Time for bed

Relaxing on the couch, your watchful limbic system is deactivated and sleep comes all too easily. Once you move to the bedroom, your brain remembers there could be danger waiting—sounding the alarm and jolting you into alertness.

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