Lack of sleep leads to dehydration

While we are asleep in bed, some parts of our body are under high pressure: the immune system is looking for pathogens, the liver breaks down toxins and converts nutrients, our brains store new knowledge in long-term storage.

If we sleep too little, it makes us moody and unfocused, more susceptible to infections, and increases our risk of serious health problems: sleep deprivation, for example, promotes the development of obesity and hypertension and increases the risk of preterm birth in pregnant women.

Now researchers have discovered another effect that lacks sleep on our body: it interferes with the "management" of the fluid balance of the body and ensures that we wake up dehydrated.

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Those who sleep little are more often dehydrated

Scientists around Asher Rosinger at Pennsylvania State University analyzed urine samples from 25,000 subjects in China and the US who had previously provided sleeping habits. They specifically searched for biomarkers in the urine that indicate dehydration.

The result: participants in the study, the sleeping on average six hours or less per night was on average more dehydrated as subjects who received about eight hours of sleep per night.

According to the researchers, the key role in this respect is the so-called antidiuretic hormone. The task of this hormone is to maintain a sufficient level of fluid in the body. This hormone is mainly released during sleep – usually in the last hours of sleep. Those who wake up too early miss the chance that the body will hydrate itself. The antidiuretic hormone does this by removing water from the urine and giving it back to the body.

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Glass of water in the morning fills the liquid storage

According to the authors of the study, dehydration can make us so bruised after a sleepless night. They advise you to start the day after a short night with a glass of lukewarm water – this replenishes the liquid storage. Cold water is less suitable because the body has extra work to heat the water to body temperature.

Rosinger, Asher Y., et al. (2018): Short-sleep duration is associated with inadequate hydration: cross-cultural evidence of American and Chinese adults, in: Sleep.