Coffee and tea are incredibly healthy beverages, considering they contain caffeine, which is a substance that may boost your mood, metabolism and mental and physical performance. Studies have also shown that Caffeine is safe for most people when consumed in low-to-moderate amounts. However, high doses of this substance may have unpleasant and even dangerous side effects. It’s true that caffeine increases alertness by triggering the release of adrenaline, the “fight-or-flight” hormone associated with increased energy. Yet, at higher doses, these effects may become more pronounced, leading to anxiety and nervousness. Besides, caffeine can help you stay awake during the day, but it may negatively impact your sleep quality and quantity. Therefore, you should cut off your caffeine consumption by the early afternoon to avoid sleeping problems.