Consuming coffee, and thus caffeine, stimulates alertness by blocking adenosine, a sleep-inducing substance. While individual tolerance varies, women may metabolize caffeine slower due to hormonal factors. The Voedingscentrum advises a maximum of five cups of coffee (400 mg caffeine) daily, with no more than 200 mg at once, to avoid side effects like headaches and rapid heart rate. Moderate consumption of two to four cups per day is linked to a ten percent reduced risk of cardiovascular diseases and strokes, attributed to antioxidants, not caffeine itself. To prevent sleep disruption, it's recommended to avoid coffee eight to twelve hours before bedtime, with the exact timing dependent on individual sensitivity and sleep schedule.