Caffeine typically lasts in your system with a half-life of about 4 to 6 hours, meaning it takes around that time to eliminate half of the caffeine consumed. However, caffeine can stay in your system for 10 to 12 hours or more depending on individual factors like genetics, age, body weight, and metabolism. Its noticeable effects usually last 4 to 6 hours but can sometimes persist up to 12 hours, which is why caffeine consumed later in the day can still affect your sleep.