Two major reviews flag caffeine as a potential trigger

—New studies reveal that sudden caffeine changes may spark manic or mixed episodes in people with bipolar disorder, disrupt sleep, and even alter how well lithium medication works.

Scientists from King’s College London, the University of Pavia and others analyzed research linking everyday caffeine use—from coffee to energy drinks—with mood instability and treatment complications in bipolar disorder. Their findings, recently published in Bipolar Disorders, suggest an overlooked trigger that may affect millions managing the condition.

One comprehensive review looked at 17 prior studies involving case reports, clinical data, and medical records. Many individuals developed manic or mixed mood episodes after abruptly increasing caffeine intake.

A broader systematic review reinforced these findings and added that caffeine’s stimulant effects may worsen mood swings. It can disturb sleep—a well-known mood trigger—and speed up lithium metabolism, potentially leading to lower blood concentrations. Lithium is frequently prescribed for bipolar patients.

Beyond mood symptoms, researchers found that some patients with bipolar disorder reported greater physical side effects than people without the condition. These included light-headedness, palpitations, and a racing heart after caffeine intake.

Another study compared caffeine intake and blood levels among smokers diagnosed with bipolar disorder, schizophrenia, or no psychiatric illness. Those with bipolar disorder had the highest average caffeine consumption and the highest measured blood levels of caffeine.

Caffeine blocks adenosine—a brain chemical that promotes sleep—which can lead to insomnia or disrupted rest. Poor sleep is one of the most reliable precursors to manic episodes.

While rare, there is also evidence that very high caffeine intake can cause psychotic symptoms—such as delusions or paranoia—in vulnerable individuals. Though uncommon, this shows how overstimulation may provoke severe mental health effects in certain cases.

Researchers call for more targeted studies to determine safe caffeine levels, frequency of use, and its long-term effects on bipolar disorder. Meanwhile, they advise patients to consult their healthcare providers about caffeine use and consider moderation and consistency—not sudden changes—as part of their wellness plan.

Sources: The impact of caffeine consumption on clinical symptoms in patients with bipolar disorder: A systematic review” and “Caffeine Levels and Dietary Intake in Smokers with Schizophrenia and Bipolar Disorder.”

Comment from a reader: This is a good reminder to monitor changes in lifestyle to help control bipolar symptoms. It’s hard for me to say if increased caffeine consumption came before or followed my manic episode. I remember it after the mania struck. But the increased consumption, especially in energy drinks, seemed to make the mania worse and/or prolonged the episode.