Why Your "Pre-Sleep Window" Is So Important + Exactly How To Fill It

One reason to be picky about your just-before-bed activities traces to human psychology. As Laura Faiwiszewski, Psy.D, a clinical psychologist at NY Health Hypnosis & Integrative Therapy, explains, when we feel an emotion while watching or reading something—say, anxiousness from watching stressful news—we have trouble separating that emotion from our own lived experience. Once we start to feel physically anxious, we may subconsciously search for experiences from our days that justify it. We grasp for reasons to feel anxious—and inevitably, we find them.

"We're not great at then shifting and compartmentalizing what we just experienced," Faiwiszewski explains. "If you look for something to be anxious about, you will find it. There's always something to be anxious about. Then we label our experience as anxiety."

And no surprise here: thinking about all the things you have to feel anxious about before bed won't be conducive to falling asleep quickly1. Beyond a racing mind, the physical manifestations of stress, concern, and fear—such as increased heart rate, blood pressure, and cortisol—are known to delay sleep onset and harm sleep quality2.

As my experience shows, the last things we take in before bed also have a way of seeping into our dreams. "You're priming yourself to think in that way before I go to sleep," explains Faiwiszewski, and your brain then takes that momentum and carries it into the dream realm. This phenomenon has a name: the Tetris effect.

Named for the simple but addictive video game, the Tetris effect theory, originally coined in the 1980s, says that when we focus on something for extended periods of time, it will inevitably shape our thoughts, perceptions, and dreams.

By this logic, it makes sense that my pre-bed literature has led to some pretty gnarly nightmares. But on the flip side, it also means that focusing my attention on something more positive before bed can set me up for easier sleep and constructive dreams.

The Tetris effect is why Tara Swart, MD, Ph.D. spends the last few moments of every day looking at her "action board" filled with photos of her goals and desires. "I look at the board, visualize it as if it is already true, feel what that feels like in all my senses, and give gratitude for it becoming real," she writes in an article on her wind-down routine. "That leads to the priming of the brain as it chooses what to filter out/tag as important to you thriving the next day."

"The things that we consume before bed can allow us to relax and help us have more sound sleep," echoes Faiwiszewski.

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