This will be very personal to each individual. Some may experience uncomfortable caffeine withdrawal symptoms such as headaches, weight changes, dizziness, anxiety, irritability, mood swings, sluggishness, insomnia, and even flu-like symptoms at times. These should last two days to a week at most. However, once this phase passes and the body adjusts to its new normal, better sleep is often reported. Quitting coffee may also help to lower blood pressure because the cardiovascular system doesn’t need to work as hard anymore.