How to stay up later

Nutritious snacks
Diet is another important factor that affects attention. Staying long periods without eating and even eating too much at once can make you lazy and slow. To end this effect, many are betting on caffeine and sugar foods. The problem with this is that you get only a momentary sensation. The best solution to keep alert: Small nutrient-rich snacks like iron and fiber.

Water
Staying hydrated is critical to avoiding fatigue, confusion and even heart palpitations. This is because water is critical for bringing oxygen to the blood and brain. A Tufts University study found that a small lack of water - 1% to 2% - can already cause fatigue and tiredness.