Understanding dehydration and sleep

Your first bathroom visit of the day is a report card. Not for your gut. For your sleep.

In the final hours of sleep, your brain releases a hormone called vasopressin. It signals your kidneys to retain fluid rather than excrete it — keeping you hydrated through the night. But vasopressin follows your sleep cycle. Miss those final hours, and your kidneys never get the signal.

The result shows up in your urine the next morning.

A Penn State study of nearly 20,000 adults found that people sleeping 6 hours have up to 59% higher odds of waking up inadequately hydrated compared to those sleeping 8. That hormonal feedback loop is driving more than tiredness.

Most people notice they feel off after a short night. Foggy. Slow. They blame the sleep. But they're also starting the day already dehydrated — and they have no way to know how bad it is.

This is where Throne changes things.

Every morning, Throne tracks your urine color and concentration. It updates your Hydration Score with each bathroom visit. And over time, it shows you something no wearable can: how your previous night's sleep is showing up in your body the next morning.

Your WHOOP tells you your sleep score.

And Throne tells you what that score actually cost you.

Launching March 10th.

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What is Vasopressin?

Vasopressin (also called antidiuretic hormone, or ADH) is a peptide hormone produced in the hypothalamus and released by the posterior pituitary gland. Its two primary functions are:

‍Water regulation — It acts on the kidneys (specifically the collecting ducts) to increase water reabsorption back into the bloodstream, concentrating the urine and helping maintain fluid balance. This is why it's called "antidiuretic" hormone — it reduces urine output.

Blood pressure support — At higher concentrations, it causes vasoconstriction (narrowing of blood vessels), which raises blood pressure. This is where the name "vasopressin" comes from.

It's released in response to signals like increased blood osmolality (your blood getting too concentrated), decreased blood volume, or low blood pressure. It also plays secondary roles in stress response, social bonding, and circadian rhythm regulation.

Clinically, synthetic vasopressin (like desmopressin) is used to treat conditions such as diabetes insipidus (where the body can't concentrate urine properly), certain bleeding disorders, and as a vasopressor in critical care settings like septic shock.