You know the feeling: the word is right there, but your brain refuses to hand it over. You had a juicy piece of gossip and halfway through telling the story, you lose track. Or you walk into a room and immediately forgetl why. Or reread the same sentence enough times that it starts to feel personal.
A lot of people write off these lapses as a busy brain, or an inevitable part of getting older (well before we are old enough to legitimately use that excuse). But Daniel Amen, MD, who has spent decades studying brain activity through imaging, says that brain fog can be a signal worth paying attention to. “People often tell me, ‘I have brain fog,’” he says. “I tell them brain fog isn’t a diagnosis, it’s your brain asking for help.”
What’s happening in a foggy brain
Dr. Amen’s research is built on SPECT imaging, which maps blood flow across the brain pooled from a database of more than 250,000 scans. “On a SPECT scan, we often see lower blood flow and decreased activity in the areas responsible for attention, focus, and memory,” he says. Every brain tells a different story, though. “No two brains look exactly alike. That’s why I don’t like guessing. I like looking.”
Part of the picture is just how demanding the brain is. “Your brain is only about 2% of your body weight, but it uses about 20% of the calories and oxygen you consume,” Dr. Amen explains. When something throws that system off, the brain registers it almost immediately. “When you feel mentally off, your brain is telling you it needs attention.”
The most common triggers
The usual suspects, according to Dr. Amen, are poor sleep, chronic stress, ultra-processed foods, alcohol, hormonal shifts, anxiety, depression, ADHD, vitamin deficiencies, certain medications, and a history of concussions. What most concerns him is how quickly people accept fog as inevitable, or nothing to worry about. “Too many people accept brain fog as normal because they’re busy or getting older. It’s common, but it isn’t normal,” he says. “You’re not stuck with the brain you have. You can make it better.”
How to know if it’s a memory or attention problem
A lot of what seems like simple forgetfulness is actually a focus issue. “Memory begins with attention,” Dr. Amen says. “You can’t remember what you never paid attention to in the first place.” Improve attention, he says, and memory often improves along with it.
That helps explain another strange but common phenomenon. Raise your hand if you’ve ever recalled a song from two decades ago without effort, but forgot why you just walked into a room. “Those are two very different brain functions,” he says. “Music is tied to emotion and repetition, which makes it easier for the brain to store for years. Walking into a room depends on working memory and attention.” Stress, distraction, multitasking, and poor sleep can make that original intention easier to lose. “It doesn’t necessarily mean your memory is failing. Sometimes it simply means your brain is overloaded.”
The blood sugar connection
Blood sugar swings play a bigger role in mental clarity than most people give it credit for. “Your brain loves stability,” Dr. Amen says. “When blood sugar spikes and crashes, your energy, mood, and focus often crash with it.” Over time, he says those swings can also cause inflammation.
He highly recommends building meals around protein, healthy fats, colorful vegetables, and fiber instead of relying on quick sugar hits for energy. He also says people often notice sharper focus within hours of a meal built around protein, omega-3 fats, and berries, paired with good hydration. Your brain gets thirsty!
Little habits that might be contributing to the fog
Beyond diet, Dr. Amen lists what he calls “brain thieves”. It’s the classics: poor sleep, chronic stress, too much alcohol, but it’s also more insidious things like sitting all day, constant multitasking, doomscrolling, and social isolation. “People think these habits are harmless because everyone is doing them,” he says. “They’re common, but they’re not good for your brain. Small daily choices add up, for better or worse.”
When it’s time to see a doctor
Occasional forgetfulness like a missed name or word here and there usually isn’t cause for major concern. But Dr. Amen flags three signs that warrant prompt medical attention: brain fog that comes on suddenly or gets worse quickly; memory problems that begin interfering with everyday life; or brain fog accompanied by confusion, severe headaches, weakness, personality changes, or trouble speaking. “Your brain deserves the same attention you’d give your heart,” he says.
A quick reset when brain fog hits
When fog starts to roll in mid-afternoon, Dr. Amen’s go-to fix doesn’t cost a thing. “Walk daily, like you’re late,” he says. Even a brisk 10-15-minute walk can increase blood flow to the brain and help with focus, energy, and mood. Don’t have time to go outside? He suggests standing up, stretching, drinking water, and stepping away from your screen for a few minutes. “Your brain wasn’t designed to stay ‘on’ all day.”
How Dr. Amen keeps his own brain sharp
Even after four decades of studying brain scans, his own routine is pretty simple. “I protect my sleep because that’s when the brain cleans and repairs itself. I make movement a daily priority because exercise is medicine for the brain.” Before big or small decisions, he runs them through two filters by asking himself, “Is this good for my brain or bad for it?” and “Does it make the world a better place?”
After more than four decades studying the brain, Dr. Amen says the biggest takeaway is that brain health isn’t necessarily fixed. “When your brain works better, you work better,” Dr. Amen says. “You’re not stuck with the brain you have. You can make it better, and when you do, you can change your life.”