Do you ever pee "just in case?"
Do you routinely go to the bathroom before you leave the house, go into a meeting, go to bed, workout etc…? You may be training your bladder to signal your brain that it is time to empty before the bladder is actually full. A healthy adult bladder can hold up to 2 cups or 16 ounces of urine during the day and can stretch more at night while you are sleeping. When the bladder is about halfway full, stretch receptors from the bladder muscle stimulate a reflex telling your bra