Caffeine

Caffeine can boost alertness, cognitive and physical performance, and may have other health effects; its benefits depend on timing and context.

• Over 90% of adults consume caffeine regularly: It blocks adenosine’s sleepiness signal and is commonly used to feel more energized and focused. 1
• Performance effects: Caffeine can improve reaction time, focus, memory, coordination, mood, and exercise performance. 2
• Neuroprotection: Regular caffeine consumption may help offset the probability of Parkinson’s and possibly Alzheimer’s-related dementia; Huberman links this potential benefit to increased release of dopamine, epinephrine, norepinephrine, and acetylcholine. 3
• Timing and context: Alertness can rise within about five minutes, peak around 30 minutes, and persist for up to 60 minutes, particularly when caffeine is taken without much food in the stomach. Effects may be more pronounced after several days of abstinence or on an empty stomach. 4 5
• Hydration: Because caffeine can increase fluid and sodium loss, Huberman recommends drinking at least an equal volume of water alongside it, ideally with a small amount of salt or electrolytes. 6
• Topical caffeine and hair: Topical caffeine may support hair maintenance by inhibiting PDE and indirectly increasing IGF-1. Huberman describes it as potentially comparable to minoxidil, with fewer reported side effects, while noting the evidence is less extensive. 7
• Study caveat: Caffeine studies often compare performance after caffeine is given to regular users who were first made to abstain and experience withdrawal; that may exaggerate the observed performance benefit. 8