Overview

• Caffeine binds to adenosine receptors in the brain, masking natural signals of tiredness.
• This receptor blockade stimulates neural activation and releases dopamine and norepinephrine to boost alertness.
• The drug’s approximately five-hour half-life means its stimulatory effects can persist and interfere with sleep.
• Experts recommend limiting intake to 400 mg per day to secure neuroprotective and cardiovascular benefits and advise avoiding consumption after mid-afternoon to prevent sleep disruption.
• Regular caffeine use can lead to dependence, and abrupt cessation often triggers withdrawal symptoms such as irritability, fatigue and headaches.