Toddlers do tend to sleep more when dehydrated as dehydration in babies and toddlers can cause excessive sleepiness as well as sunken eyes, sunken soft spot on babies head and cold or dry skin and dry mouth.
Also little or no urine for 8 hours is another sign of dehydration in toddlers and babies.
You should be worried about dry diapers when the baby or toddler has no wet diapers or very little wet diapers within 6 hours to 8 hours.
If your baby hasn't peed in 10 hours or has a wet diaper longer than 6 to 8 hours then it's a sign that the baby is dehydrated and needs more fluids and usually needs to see a doctor.
8 hours is too long without a wet diaper in both babies and toddlers.
Babies should have at least 6 wet diapers per day and toddlers should have at least 4 to 5 wet diapers per day although 3 year olds may only have 2 wet diapers to 3 wet diapers per day which is normal.
Fewer than 6 wet diapers per day is dehydration in babies.
If your baby is having at least 6 wet diapers per day then they are hydrated enough but if the baby has less than 6 wet diapers a day then they are usually dehydrated.
If your baby or toddler has no wet diapers within 8 hours then they are most often dehydrated and should see a doctor.
If your baby or toddler is having very watery or diarrhea like poop then it means the baby or toddler is losing water.
Fewer than 2 to 3 wet diapers in 24 hours is considered dehydration in toddlers.
A toddler should have at least 3 wet diapers per 24 hours although some well hydrated toddlers have 4 to 5 wet diapers in 24 hours.
If an infant has less than 6 wet diapers in 24 hours then that is a sign of dehydration in the infant.
A toddler should have at least 3 wet diapers per day in 24 hours depending on how much they drink and how often they pee.
If the toddler has fewer than 3 wet diapers in 24 hours then they could be dehydrated and if the toddler has not had a wet diaper in 6 hours then they are dehydrated and should see a doctor or go to the ER.
If the toddler has had no wet diaper in 8 hours then they are most certainly dehydrated and you should take them to the ER.
If the toddler or baby has no wet diaper within 4 to 6 hours then that is considered too long to go without a wet diaper.
Babies under 2 years old will usually pee more often when hydrated and should have a wet diaper every 1 to 2 hours or so.
If the diaper is still dry after 5 hours to 6 hours then it could be a sign of dehydration.
However if it's a toddler older than 2 years old then they can sometimes go 2 to 3 hours without wetting and then they will wet all at once.
You should take your toddler to the ER for dehydration if they are under 2 years old and they have had no wet diapers within 3 to 4 hours.
Or if the toddler is 2 or above and has had no wet diaper within 5 to 6 hours then you should take your toddler to the ER to be sure they are okay.
Or if you notice any of the signs below that your toddler is dehydrated then you should take the toddler to the ER.
Dry tongue and dry lips.
No tears when crying.
Fewer than six wet diapers per day (for infants), and no wet diapers or urination for eight hours (in toddlers).
Sunken soft spot on infant's head.
Sunken eyes.
Dry and wrinkled skin.
Deep, rapid breathing.
You should be concerned about a dry diaper if the baby under 2 years old has not peed within 3 to 4 hours and if the baby is older than 2 and has not peed within 6 hours then you should take the child to the hospital or urgent care.
If the baby seems weak or pale looking then take the child to the hospital as they could be dehydrated.
The length of time that is too long for no wet diaper depends on the age of the baby or toddler.
For babies under 2 years old if they haven't had a wet diaper within 3 hours then that would be too long for no wet diaper.
If the baby is 2 years old or above then longer than 6 hours or longer would be too long for no wet diapers.
Younger babies should pee more and have more wet diapers than an older baby or toddler.
Depending on age of the toddler some toddlers can have a dry diaper for an hour or as long as 3 to 4 hours.
And in some cases older toddlers such as 2 years old and 3 years old may have a dry diaper for as long as 5 to 6 hours and then suddenly pee at once.
This is usually because they are gaining some bladder control and are holding it in and then releasing the pee at once.
When properly hydrated a 2 year old boy should pee every 30 minutes to an hour.
Although it's also normal for some 2 year olds to pee only every few hours or so.
If the 2 year old has not peed within 6 to 8 hours and they are drinking enough then you should take the child to the doctor or urgent care to make sure they are properly hydrated.
Ideally a 2 year old baby should pee every 30 minutes to an hour.
Although it's also normal for a 2 year old baby to only pee every few hours or even every 3 hours.
As long as they are drinking enough fluids and having at least a few wet diapers per day then they are okay.
A 2 year old can go as long as 6 hours in some cases without a wet diaper.
However most often a 2 year old will only go as long as 2 hours to 3 hours without a wet diaper depending on how much they drink.
If it's hot outside then the 2 year old will sweat more and not produce as much urine and so they may go a few hours or even 4 hours without a wet diaper which is normal.
Some 2 year olds pee as often as every 20 to 30 minutes and some go as long as 1 hour to 2 hours and even 3 hours without peeing.
It is normal for a 2 year old boy to go 2 hours and sometimes even as long as 3 hours with a dry diaper before they pee.
My 2 year old sometimes goes 2 hour and sometimes as long as 3 hours before he wets his diaper.
At 2 years old they sometimes hold the pee in for a few hours and then once they feel their bladder filling up and get the urge to pee they then let lose.
If the 2 year old boy has not peed within 6 hours then I would be concerned about dehydration.
But sometimes toddlers and 2 year olds pee different amounts during the day.
Some days my 2 year old son pees every 30 minutes and has a wet diaper ever few hours and then some days he just does not pee as often and can have a dry diaper for 2 to 3 hours.
As long as you're keeping your toddler hydrated with water, juice etc then they should be okay.
But if the 2 year old boy has no wet diapers within 6 to 8 hours then I would take them to the doctor or urgent care to be checked out.
Some 2 year olds go through 4 to 5 diapers per day while some days some 2 year olds pee less and may only go through 2 to 4 diapers per day.