top of page
mlve hc logo high res.png

Are you having the fuzzy feeling in the morning?

In a 2018 Penn State study, it was found that it could be due to dehydration caused by short sleep hours, which led to symptoms of inadequate sleep, such as fatigue, fuzzy thinking, and headache in the morning!

Adults who sleep only 6 hours and less at night may have a 59% higher chance of being dehydrated, with more concentrated urine, compared with those who sleep longer 7 to 8 hours on a regular basis.

Sleeping more than 9 hours show no link to the symptoms of dehydration.

The researchers suggest that the findings may show the effect of the water-balance regulating hormone called vasopressin.




What happens to my kidneys during sleep?

During sleep, the pituitary gland in the brain releases vasopressin to signal kidneys to store the fluid in the body, rather than excreting it through urine. Normally, in a later part of the sleep cycle, the pituitary gland will release more of the vasopressin.

Thus, if you wake up earlier due to the shorter sleep duration, lesser vasopressin hormone were produced and kidneys do not receive information to store more water.


What can I do to feel better after waking up from the short sleep?

Try to get adequate sleep for the rest of the days, and try drinking at least a glass of water when you wake up in the morning.  Drink extra water during the other times of the day too!


What are other effects of dehydration to my body functions?

In a short term, it affects mood, physical performance, and in a long term, chronic dehydration may increase risk of urinary tract infections and kidney stones.


What are the signs of dehydration?

Common symptoms are dry mouth/tongue, thirst, headache, and lethargy. Less recognized symptoms are fatigue, lack of focus, headache, dizziness, light headedness, muscle weakness, rapid breathing and muscle cramps.


What are other causes of water loss during sleep?

Water are lost during breathing, especially if someone breathes through mouth, snores or have sleep apnea; an overly dry or warm bedroom also lead to extra water loss; an intense exercise at night may also cause insufficient rehydration in time before bed. Alcohol drinks are also one of the factors that increase water loss.

If you find that excessive sleepiness is constantly bugging you even with more than 6 hours of sleep, it could be a sign of disorder that results in poor sleep quality and metabolism issues in a long term. It is advisable that you address this with your healthcare provider.

(updated : December, 2019)



Disclaimer : The website may contain information relating to various conditions and treatment, gathered and sourced from reputable sources. However, this is not a substitute for professional medical advice, diagnosis or treatment, it is solely intended for informational purposes only. Patients should always consult with a doctor or healthcare provider for thorough medical advice and information about diagnosis and treatment.



  1. Rosinger, 2018. Short sleep duration is associated with inadequate hydration: Cross-cultural evidence from US and Chinese adults.

  2. Shaheen, 2018. Public knowledge of dehydration and fluid intake practices: variation by participants’ characteristics

  3. The connection between hydration and sleep. National Sleep Foundation.


Similar Articles

Alzheimer, is it a preventable condition?

Alzheimer’s disease, is the most common form of dementia .....

continue reading

bottom of page