Lack of water can cause you to experience periods of fatigue and low energy as your body tries to function without enough water. If you're constantly feeling sluggish and tired despite getting a quality night's sleep, you may need to boost your water intake.

Why does dehydration cause lethargy?

That's because your body needs to be properly hydrated to feel energized and function optimally. Here's what happens when you're dehydrated: As dehydration sets in, your blood pressure drops, leading to poor circulation and reduced blood flow to your brain. This causes feelings of sleepiness.

Why does dehydration cause diarrhea?

Diarrhea – the most common cause of dehydration and related deaths. The large intestine absorbs water from food matter, and diarrhea prevents this from happening. The body excretes too much water, leading to dehydration. Vomiting – leads to a loss of fluids and makes it difficult to replace water by drinking it.