Not knowing can feel worse than bad news, and tolerance for it can grow

Key takeaways

• In a 2016 University College London experiment, volunteers’ stress tracked how unpredictable a mild shock was, using a computer model in which unpredictability peaks at coin-flip odds¹.
• Across 181 studies and more than 52,000 people, trouble tolerating uncertainty went hand in hand with symptoms of anxiety, depression, OCD and eating disorders⁴.
• In a survey of 222 people with advanced cancer, published in 2022, 55% reported anxiety tied to their scans, and it peaked while they waited for results⁸.
• A 2023 review of 26 studies found that talk therapy lowered intolerance of uncertainty in people with generalized anxiety disorder, and their worry dropped too⁵.
• You can practice small doses of not knowing and plan your waiting periods, but if worry starts causing problems at work, at school or at home, NIMH advises getting professional help¹³.

Forty-five volunteers at University College London spent a session turning over rocks on a computer screen¹. Some rocks hid a snake. A snake meant a mild but real electric shock to the left hand¹².

The odds kept shifting as the game went on. For a stretch, one rock might hide a snake 9 times out of 10. Later, it was a coin flip¹. Every few turns, people rated their stress while the team tracked their pupils and the sweat on their skin¹.

The pattern was striking. Stress didn’t simply climb with the chance of pain. It tracked unpredictability, which the team estimated with a computer model¹.

In that model, unpredictability is highest when a shock seems about as likely as not, and lower when you can be fairly sure either way, even fairly sure a shock is coming¹. People’s stress ratings, pupils and sweat rose and fell with it¹.

In the university’s news release, lead author Archy de Berker put it simply: being unsure whether a shock is coming is far worse than being certain either way².

Most of us know this from life. Waiting on a biopsy, a layoff list or an election can feel worse than the news itself.

This article covers why not knowing is so hard, why some people find it harder than others, and how to build your tolerance for it, with a toolkit for your next waiting period.

Your stress system tracks the odds, not just the danger

The UCL game ran for 320 rounds, and the odds switched every 26 to 38 rounds¹. The stress was real: saliva samples showed the stress hormone cortisol rising about 20 minutes after the first shocks¹.

Their model estimated how uncertain each person felt on each turn. They separated several kinds of not knowing. One is what you haven’t learned yet. Another is plain randomness that no amount of learning can remove¹.

The randomness, not the gaps in learning, best explained people’s stress ratings, and it also tracked their pupil size and sweating¹.

This is the surprise. People whose stress followed the uncertainty most closely were better at guessing where the snakes were¹. Senior author Sven Bestmann suggested that stress may help us learn about dangers we can’t predict, which could have helped our ancestors survive².

So the jittery feeling of not knowing isn’t a flaw. It’s an alarm doing its job. The trouble comes when the alarm keeps ringing long after it has anything useful to tell you.

The fine print matters. The news release said stress was lowest when the chance of a shock was zero or 100%². But the game never offered a sure thing. The most predictable rocks hid a snake 90% or 10% of the time¹.

And the coin-flip peak comes from the model’s math. The paper didn’t directly compare people’s stress ratings at each level of odds¹.

It was also one experiment with 45 young adults, using shocks rather than everyday worries like money or health¹. The authors note that long-running stress may work differently¹. The work was funded by public and charitable sources, including the UK Medical Research Council and the Wellcome Trust¹.

Some people find the unknown harder to bear, and it shows

Psychologists have a name for struggling with not knowing: intolerance of uncertainty. R. Nicholas Carleton of the University of Regina describes it as a lasting difficulty enduring the unpleasant feeling that comes when information seems to be missing³.

Carleton has argued that fear of the unknown is a core ingredient shared by many anxiety-related problems³.

Researchers measure the trait with the Intolerance of Uncertainty Scale, first published by Freeston and colleagues in 1994, and a 12-item short form from 2007³. People rate how well a series of statements about uncertainty describe them. The scale is copyrighted, so its items aren’t reproduced here.

The trait shows up across many conditions. In 2019, researchers led by Peter McEvoy pooled 181 studies with 52,402 people⁴. Intolerance of uncertainty had a moderate link with symptoms of generalized anxiety, social anxiety, panic, obsessive-compulsive disorder (OCD), depression and eating disorders⁴.

That’s a link, not proof of cause. Studies like these can’t show whether the trait leads to anxiety, anxiety feeds the trait, or both.

Researchers also see a pattern in what people do when they can’t stand not knowing. A 2025 review by Jayne Morriss of the University of Southampton describes “safety-seeking” behaviors, such as avoiding a situation, gathering more and more information, and checking⁷.

Each one brings quick relief. But research on exposure suggests people learn that the unknown is manageable by facing it without these habits⁷.

That may sound familiar if you’ve ever refreshed a patient portal every hour, read 40 reviews before a small purchase or scrolled the news late into the night. Our article on health information overload has tips for a calmer information diet.

Waiting is its own kind of stress

People living with cancer have a word for the dread around medical imaging: “scanxiety.” A University of Sydney thesis defines it as the distress people feel before, during and after a cancer scan⁹.

In a survey at several cancer centers, published in 2022, a University of Sydney team asked 222 people with advanced cancer about their recent CT scans⁸⁹. More than half, 55%, reported scanxiety. Among them, it averaged 6 on a 10-point scale and peaked while they waited for results⁸.

Waits weren’t short. Seven in 10 waited more than two days⁸. Younger patients, and those living far from a big city, were more likely to have it⁸. Across 57 earlier studies, reported rates ranged from 0% to 83%, and the studies measured it in many different ways⁹.

Few researchers have studied waiting as closely as Kate Sweeny, a psychologist at the University of California, Riverside, whose lab has focused on it since 2008¹⁰. In one project, her team surveyed 50 law students six times across the four months between the California bar exam and their scores¹⁰. Distress ran highest early in the wait and again as results day neared. On average, optimists felt less anxious and ruminated less, meaning they spent less time replaying the same worries¹⁰.

One finding is easy to act on. When Sweeny’s team surveyed health care providers for a 2017 paper, 93% said they delivered test results on no fixed timeline, telling patients they’d hear once results came back¹⁰. Her fix is simple: book a specific time to go over the results, so patients aren’t left guessing¹⁰.

You can ask for that yourself: “When will the results be ready, and can we set a time to go over them?”

Uncertainty isn’t only personal. In the American Psychological Association’s 2025 Stress in America survey, run by The Harris Poll in August with 3,199 U.S. adults, 76% said the future of the nation was a significant source of stress in their lives¹². That was nearly unchanged from 77% just before the 2024 election¹².

Tolerance for uncertainty can be trained

Intolerance of uncertainty isn’t fixed. Some of the best evidence comes from people with generalized anxiety disorder (GAD), a condition built around hard-to-control worry.

In 2023, researchers Wilson, Abbott and Norton pooled 26 studies with 1,199 adults with GAD⁵. Psychological treatment lowered intolerance of uncertainty by an amount the authors called large. Worry, anxiety and depression dropped, too⁵.

Cognitive behavioral therapy (CBT) aimed squarely at uncertainty beat general CBT at the end of treatment. But by follow-up, that edge had faded⁵. The more session time therapists spent on uncertainty, the bigger the gains⁵.

One focused method is the behavioral experiment. You make a prediction about what will happen if you face uncertainty, try it, and compare the result with what you feared.

Psychologist M.J. Dugas and colleagues tested the approach. They randomly assigned 60 adults with GAD to 12 weekly one-hour sessions of these experiments or to a waiting list⁶. The treated group improved more on every measure, and the gains held or grew a year later⁶.

That trial compared treatment with a waiting list, not another therapy, so it can’t show this method beats others.

Other approaches help, too. Morriss’s 2025 review cites a 2023 meta-analysis in which cognitive approaches, exposure and mindfulness each lowered intolerance of uncertainty⁷. The mindfulness result came from only five studies⁷.

A note of caution: a 2024 analysis that compared therapy against active comparison treatments, rather than no treatment, found no clear edge, though it included just four studies⁷.

NIMH also lists acceptance and commitment therapy (ACT) as a treatment option for GAD. It encourages accepting thoughts without judgment and draws on mindfulness and goal setting¹³.

Your uncertainty toolkit

These tools are our own design, built from the research above. They haven’t been tested as a package. They are practice for everyday uncertainty, not a treatment for an anxiety disorder.

Step 1: Sort it. When a worry shows up, write it down, then put it in one of three bins.

Bin	What it sounds like	What to do
I can act	“The bill is due Friday.”	Pick one next step and a time to do it.
I can prepare	“The layoff list comes out next month.”	Make a backup plan, then set it aside.
I can’t control	“What if the scan shows something?”	Notice the worry, name it, and return to what’s in front of you.

Most worries land in the middle. Preparing is different from rehearsing disaster. A plan has steps and an end point. Worry loops.

Step 2: Climb a small-uncertainty ladder. This borrows the logic of behavioral experiments⁶. Before each step, rate from 0 to 10 how uncomfortable you expect to feel. Afterward, rate how it went.

1. Order a dish you’ve never tried without reading reviews.
2. Take a new route to a familiar place without previewing it.
3. Let a nonurgent text sit for an hour before replying.
4. Skip the weather app for a day and dress for what you see out the window.
5. Make a small purchase after reading only two reviews.
6. Check a patient portal or job inbox once a day, at a set time.

Stay on a rung until it feels easy, then move up. The point is to compare your prediction with what happened.

Step 3: Plan the wait. Use this before a biopsy, a job decision or any result you’re dreading.

• Before: Ask when and how results will come, and whether you can schedule the call¹⁰. Choose one person to tell, and one person to be with you when the news arrives.
• During: Fill some hours with absorbing activities, the kind that take skill and hold your full attention. Sweeny’s lab calls this state “flow.” In a 2019 study of three groups facing nerve-racking waits, getting absorbed, whether in a favorite activity or a game of Tetris, made the time easier to bear¹⁰¹¹.
• During: Pick one daily checking time for news, portals or email. Keep your usual sleep, meals and movement.
• Near the end: Sweeny’s lab suggests preparing emotionally and practically for bad news¹¹. Write down your first two steps for each possible answer.
• After: Whatever the news, plan something kind for yourself that day.

What the evidence shows

Claim	Evidence level	What studies found
Uncertainty itself drives short-term stress	Promising but early	One lab study of 45 adults using shocks1
Intolerance of uncertainty is linked to anxiety and related symptoms	Strong evidence	181 studies, moderate link; can’t show cause4
Talk therapy lowers intolerance of uncertainty in GAD	Strong evidence	26 studies, large effects, with less worry5
CBT aimed at uncertainty beats general CBT over time	Not enough evidence	Ahead at the end of treatment, not at follow-up5
Behavioral experiments for uncertainty	Promising but early	One trial of 60 adults versus a waiting list6
Mindfulness lowers intolerance of uncertainty	Promising but early	Five studies in one meta-analysis7
Absorbing “flow” activities ease waiting	Promising but early	Studies from one research lab1011

Living with the unknown is an old human skill

Gardeners plant without knowing what the summer will bring. Farmers, sailors and midwives have always worked with forces they couldn’t control. Patience with natural timing is a value many natural-health readers already hold.

The research adds a useful twist. Tolerating uncertainty isn’t passive. It’s a skill you practice, much like building strength, with small, steady loads.

That fits self-reliance, too. You can’t control every outcome. You can control how you prepare, where you put your attention and whom you ask for help.

If you use calming teas, herbs or supplements during a stressful wait, tell your clinician, especially if you take other medicines. Our article on telling your doctor about supplements explains why.

When worry becomes an anxiety disorder

Occasional anxiety is normal. NIMH explains that in an anxiety disorder, the anxiety doesn’t go away, shows up in many situations and can get worse over time¹⁴. About 1 in 3 U.S. teens and adults will have one at some point¹⁴.

Talk with a health care provider if you notice signs NIMH links to generalized anxiety disorder¹³:

• worry about everyday things that feels excessive or hard to control;
• feeling restless, irritable or on edge;
• trouble concentrating;
• trouble falling or staying asleep, or feeling tired;
• headaches, muscle aches, stomachaches or tension;
• anxiety that causes problems at school, at work or with friends and family.

Doctors consider GAD when hard-to-control worry happens most days for at least six months, along with symptoms like these¹³. NIMH describes CBT as well studied and the top choice of talk therapy for GAD, and medicines can help¹³. Habits like cutting caffeine, sleeping enough, exercising and mindfulness can ease symptoms alongside standard care, but NIMH says they don’t replace treatment¹³.

If you or someone you know is struggling or having thoughts of suicide, call or text the 988 Suicide & Crisis Lifeline at 988, or chat at 988lifeline.org¹³. In a life-threatening emergency, call 911¹³.

Questions readers ask

The bottom line

Not knowing is stressful by design. In the lab, stress tracked unpredictability, and that alarm may help us learn. It becomes a problem when it rings all the time, and when checking, searching and reassurance keep it going.

Tolerance for uncertainty can grow. Therapy has strong evidence for lowering it in generalized anxiety disorder. Small daily experiments, absorbing activities and a plan for waiting are low-cost ways to practice. If worry runs your days, reach out to a provider, and call or text 988 in a crisis.

Related reading

• Worry gets louder at 3 a.m., and a few tested tricks can turn it down
• Too much health advice makes people tune out, so build an information diet
• What a medical test can and cannot tell you
• What happens when you don’t tell your doctor about supplements
• How to tell psychiatrists, psychologists and therapists apart

Sources

1. de Berker AO, Rutledge RB, Mathys C, Marshall L, Cross GF, Dolan RJ, Bestmann S. “Computations of uncertainty mediate acute stress responses in humans.” Nature Communications, 2016;7:10996 (UCL Discovery open-access copy). discovery.ucl.ac.uk
2. University College London. “Uncertainty can cause more stress than inevitable pain.” News release via ScienceDaily, March 29, 2016. sciencedaily.com
3. Carleton RN. “Into the unknown: A review and synthesis of contemporary models involving uncertainty.” Journal of Anxiety Disorders, 2016;39:30–43 (University of Regina repository). uregina.scholaris.ca
4. McEvoy PM, Hyett MP, Shihata S, Price JE, Strachan L. “The impact of methodological and measurement factors on transdiagnostic associations with intolerance of uncertainty: A meta-analysis.” Clinical Psychology Review, 2019;73:101778 (abstract, NYU Information for Practice listing). ifp.nyu.edu
5. Wilson EJ, Abbott MJ, Norton AR. “The impact of psychological treatment on intolerance of uncertainty in generalized anxiety disorder: A systematic review and meta-analysis.” Journal of Anxiety Disorders, 2023;97:102729 (University of Technology Sydney record). opus.lib.uts.edu.au
6. Dugas MJ, Sexton KA, Hebert EA, Bouchard S, Gouin J-P, Shafran R. “Behavioral Experiments for Intolerance of Uncertainty: A Randomized Clinical Trial for Adults With Generalized Anxiety Disorder.” Behavior Therapy, 2022;53(6):1147–1160 (UCL Discovery record with abstract). discovery.ucl.ac.uk
7. Morriss J. “Psychological mechanisms underpinning change in intolerance of uncertainty across anxiety-related disorders: New insights for translational research.” Neuroscience and Biobehavioral Reviews, 2025;173:106138 (University of Southampton open-access copy). pubmed.ncbi.nlm.nih.gov
8. Bui KT, Kiely BE, Dhillon HM, et al. “Prevalence and severity of scanxiety in people with advanced cancers: a multicentre survey.” Supportive Care in Cancer, 2022;30:511–519. dx.doi.org
9. Bui KT. “Scanxiety: Scan-associated anxiety in patients with advanced solid cancers.” Doctoral thesis, The University of Sydney, 2022. ses.library.usyd.edu.au
10. Santoro H. “The science of uncertainty” (Kate Sweeny’s Life Events Lab, University of California, Riverside). Monitor on Psychology, American Psychological Association, November 2021;52(8). apa.org
11. Rankin K, Sweeny K. “Navigating uncertain waiting periods.” University of California, Riverside, Graduate Student Resource Center, August 26, 2020. gsrc.ucr.edu
12. American Psychological Association. “Stress in America 2025.” Survey conducted by The Harris Poll, August 2025; report released November 2025. apa.org
13. National Institute of Mental Health. “Generalized Anxiety Disorder: What You Need to Know.” NIH, revised 2025. nimh.nih.gov
14. National Institute of Mental Health. “Anxiety Disorders.” NIH, last reviewed December 2024. nimh.nih.gov