CBD for Focus: What Studies Found on Attention and Memory

What studies on CBD and concentration found

These are the main human studies, with the design, group size and dose of each.

Hippocampal blood flow and memory (2020)

In a 2020 randomised, double-blind, crossover study (opens in a new tab), 15 healthy adults took a single 600 mg dose of CBD or a placebo on separate days. Brain scans three hours later showed higher blood flow in the hippocampus, a region involved in memory, after CBD.

The volunteers also did working memory tasks (digit span and n-back) and recalled a short story. Their scores were similar after CBD and placebo. The authors noted that the study was not powered to detect small or medium effects, and that one dose in healthy volunteers may not reflect repeated use.

Driving and cognitive tests at three doses (2022)

A 2022 randomised, double-blind, crossover trial (opens in a new tab) gave 17 healthy adults placebo or 15 mg, 300 mg or 1,500 mg of oral CBD. It measured simulated driving, cognitive function and how intoxicated people felt.

No dose impaired cognition or made people feel intoxicated. The authors also found that CBD stayed in the blood for a long time, more than four weeks after the 1,500 mg dose.

What reviews of the evidence say

A 2024 meta-analysis of 16 controlled trials (opens in a new tab) looked at single doses of CBD in adults, measured up to eight hours after dosing. On objective tests of attention, memory, information processing, psychomotor skills and driving, results after CBD did not differ from placebo. The one measure that did differ was self-reported sedation, which was slightly higher after CBD. Most participants were people who rarely or never used cannabis.

A 2023 systematic review (opens in a new tab) of 23 clinical trials and 36 animal studies reached a similar conclusion: single and repeated doses of CBD did not appear to impair cognition in people without neuropsychiatric disorders. The authors called for larger, less selective trials with standardised tests and a range of doses.

What these studies cover

Most of this research was done in small groups of healthy adults in a lab, and most of it used a single dose. None of the studies compared CBD oil, capsules, gummies or other formats.

Does CBD make you sleepy or alert?

Drowsiness is one of the side effects reported most often in CBD studies.

• In the 2024 meta-analysis (opens in a new tab), self-rated sedation was the only outcome where single doses of CBD differed from placebo. The effect was small.
• The product information for Epidyolex (opens in a new tab), a prescription CBD medicine for certain types of epilepsy, lists somnolence (sleepiness) as a very common side effect, affecting more than 1 in 10 patients at 10 to 25 mg per kg of body weight per day. It says other substances that slow the central nervous system, including alcohol, can add to this effect.
• A 2019 review of CBD adverse effects (opens in a new tab) found sedation, somnolence and fatigue among the most common side effects in clinical trials. These trials were mostly in children with severe epilepsy taking other medicines.

You can read more in our guide to drowsiness and other CBD side effects. The Epidyolex product information also advises patients not to drive until they know how it affects them. Our article on driving and CBD in Europe covers the rules.

CBD and caffeine: what's known about combining them

If you drink coffee, the relevant question is how CBD and caffeine interact in the body. One clinical trial has measured this.

In a 2021 phase 1 trial (opens in a new tab), 16 healthy adults took a single 200 mg dose of caffeine. They then took prescription CBD that built up to 750 mg twice a day, and took the same caffeine dose again. With CBD on board:

• total caffeine exposure (AUC) was 95% higher
• peak caffeine level was 15% higher
• caffeine's half-life went from 5.4 to 10.9 hours

Only 9 of the 16 people finished the trial; 6 stopped because of raised liver enzymes. The authors concluded that CBD inhibits CYP1A2, the liver enzyme that breaks down caffeine. The Epidyolex product information (opens in a new tab) describes CBD as a weak inhibitor of CYP1A2 and says the clinical importance of the finding has not been studied.

The trial measured caffeine levels in the blood, not alertness or focus. If you take medicines, CBD can affect how some of them are broken down too. Our guide to CBD drug interactions has more.

Is CBD safe for students and under-25s?

EFSA's position is the most relevant one for this age group. In its updated statement published on 9 February 2026 (opens in a new tab), EFSA's NDA Panel concluded that the safety of CBD as a novel food cannot be established for people under 25, pregnant or breastfeeding women and people taking medication. EFSA also confirmed open data gaps on possible effects on the nervous system, liver, hormones and reproduction.

In the UK, the Food Standards Agency (opens in a new tab) does not recommend CBD for children under 18, people taking medication, or those who are pregnant, breastfeeding or trying to conceive, unless under medical direction.

Our short guide explains what CBD is and why it became popular, and our guide to CBD rules in each European country covers the legal side.

Other things that affect focus

The NHS lists difficulty concentrating because you're tired (opens in a new tab) as a symptom of insomnia, and names stress, alcohol, caffeine and shift work among its common causes. NHS Every Mind Matters says that finding it hard to focus on everyday tasks (opens in a new tab) can be a sign you're not getting enough sleep.

If concentration problems are new, last a long time, or affect your work, studies or safety, see a GP.

What about ADHD?

This article is about everyday focus in healthy adults, not ADHD. ADHD is a medical condition, and the NHS advises (opens in a new tab) seeing a GP if symptoms affect your studies, work or relationships, and says ADHD medicines must be started and monitored by a specialist.