Daytime Urination in Bedridden Individuals Without Sweating
Yes, you will urinate more during the day when lying in bed all day and night without sweating, because the normal nighttime reduction in urine production disappears when you remain recumbent continuously.
Why Recumbency Increases Daytime Urine Output
The key mechanism is that lying flat eliminates the normal day-night difference in urine production. 1
When you lie down, pressure changes occur in blood vessels and kidneys that increase diuresis (urine production) and natriuresis (sodium excretion), which normally happens only at night. 1
In healthy individuals who are upright during the day, urine production averages 83 ml per hour during daytime and drops to 48 ml per hour at night—a 42% reduction. 2
When you remain recumbent continuously, your body produces urine at the higher "nighttime recumbent" rate throughout the entire 24-hour period, effectively increasing total daytime output compared to someone who is upright during the day. 1
The Fluid Redistribution Effect
Chair rest immobilization for just 4 hours decreases plasma volume by approximately 6% due to blood pooling and greater fluid loss into the interstitial space in the legs. 1
This fluid redistribution from lying down causes your kidneys to filter and excrete more fluid during what would normally be "daytime" hours. 1
The absence of sweating compounds this effect because you're not losing fluid through skin evaporation, meaning all excess fluid must be eliminated through urine. 1
Normal Day-Night Patterns Are Abolished
Healthy mobile individuals void a median of 6 times daily and 0.5 times nightly (essentially once every other night or less). 2
Continuous bed rest eliminates this pattern—you'll void more frequently during traditional "daytime" hours because your body is producing urine at the elevated recumbent rate continuously. 1, 2
Nocturnal polyuria (producing >33% of 24-hour urine output at night) becomes irrelevant when you're always horizontal, as the distinction between day and night urine production disappears. 3, 4
Clinical Implications
This increased daytime urination during continuous bed rest is a normal physiological response, not a pathological condition. 1
The body prioritizes maintaining proper fluid and salt balance over convenience, so preventing this diuresis could actually be harmful to your cardiovascular and renal health. 1
If you're bedridden and notice increased urination during daytime hours, this represents normal adaptation to continuous recumbency rather than bladder dysfunction. 1, 3