Why Worrying About Tomorrow Can Disrupt Your Sleep Tonight
New research shows that anticipating a stressor changes late-night dreams.
Posted March 23, 2026 | Reviewed by Jessica Schrader
You fall asleep just fine—but in the early morning hours, you drift into stressful or negative dreams. Your sleep turns restless.
If you have something stressful coming up tomorrow—a doctor’s appointment, a presentation, or the dreaded work performance feedback—this pattern may feel familiar.
Many people experience this. I certainly have.
Years ago, my husband and I took a seven-day live-aboard sailing course in the San Juan Islands off Washington State. Our training included learning how to deal with potential catastrophes: cabin fires, hypothermia, and repeated “crew overboard” drills. Unfortunately, we never managed to rescue “Bob,” the life preserver that stood in for the overboard sailor.
I knew that toward the end of the week, we would compete in a sailing “race,” which meant going way too fast and “heeling” at about a 30-degree angle.
By day five, I was having nightmares every night.
Eventually, my poor sleep and growing dread led me to abandon ship—literally and figuratively.
To be fair, sailing wasn’t the only factor. My anxiety likely came from a perfect storm: disaster training, my husband making me watch All Is Lost (Robert Redford alone on a boat, and it does not go well), and a poorly timed white-water rafting trip with my book club, where we flipped the raft.
Like many people, I experienced anticipatory anxiety disrupting my sleep. But how does this work?
Could Dreams Be Rehearsing Tomorrow’s Stress?
Recently, a Swiss research team, Sandrine Baselgia and Björn Rasch, explored whether dreams might hold part of the answer .
They predicted that when people expected a distressing task the next day, dreams would show extra stressful content—especially as morning approached.
Previous research already hinted at this connection.
For example, a team of researchers in France documented a pattern most students can relate to. They found that right before an entrance exam for medical training, about 60% of the students dreamed of the exam. These were mostly bad dreams. Participants also reported worse sleep than usual that night.
Other investigators have looked at brain activity during sleep . In one clever experiment, the research team discovered that anticipating a stressful event caused reduced markers of high-quality sleep, such as slow-wave (deep) sleep. Interestingly, this mainly occurred late in the sleep period.
To researchers, this pattern of findings raised a question: could stressful dreams help explain why sleep deteriorates toward morning when we’re worried about the next day? If that idea is correct, it means the worries we carry into bed may literally reprogram what our brains do while we sleep.
What Happens to Dreams When Stress Is Expected Tomorrow?
Baselgia and Rasch wondered if it was the bad dreams that drove the harmful biological changes in later sleep periods. As a first step in assessing this, they tested whether an anticipated stressor would cause more stressful dreams in later sleep.
They invited young adults to spend three nights in a sleep lab:
Participants learned about the next day’s task before going to sleep.
The stressful condition involved preparing a speech and solving difficult math problems while being evaluated. The relaxing condition involved an immersive virtual environment, such as a beach or meadow.
During the night, participants were awakened up to eight times—four times earlier in the night and four times later—and asked to report what was going through their mind and then to describe any dreams.
Do Stressful Dreams Appear as Morning Approaches?
When participants expected an upcoming stressful task, their dreams became more stressful as the wake-up time drew near. This finding suggests that our brains may be reactivating concerns about the future during late-night dreaming .
This study cannot prove that stressful dreams directly cause poorer sleep.
But drawing upon multiple studies, we now know that an anticipated stressor causes both stressful dreams and poor sleep as morning approaches.
Revealing a Broader Feature of the Mind
One intriguing implication of this research is that our sleeping brain may not simply replay the past—it may also prepare us for the future. When we anticipate something stressful, the brain may reactivate related thoughts and feelings in dreams to ready us for the upcoming stressful event.
We know that something similar occurs in the daytime when we want to remember an intention—what psychologists call a prospective memory task—such as remembering to take a pill.
Research on this “intention-superiority effect” from my lab and others’ has shown that intentions show higher activation in memory than other memory contents. And just as in stressful dreams, the intention-superiority effect seems to operate automatically and get stronger as performance time approaches .
And so, in both our sleeping and waking life, our brains unconsciously anticipate future events, but in sleep, this might be disruptive.
How to Get Better Sleep: Reducing Stress and Other Techniques
The good news is that several effective, drug-free approaches can improve sleep.
The treatment with the strongest evidence currently is cognitive behavioral therapy for insomnia (CBT-I).
Experts also recommend good sleep hygiene, including:
The National Institutes of Health publishes a helpful brochure on thi s .
Stress-reduction techniques can also help, including mindfulness meditation , progressive muscle relaxation , and miscellaneous therapeutic methods .
I personally plan to try some of these strategies, and maybe I’ll relax enough to attempt sailing again. Though it’ll be in warmer water, plus I’ll be wearing an orange life vest and tied to the mast like Bill Murray in What About Bob? If I anticipate that scenario, I think I’ll have better dreams and better sleep.
This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.