Toddlers crying in their sleep are one of the most common problems that one has to deal with as a parent. According to pediatricians, it’s a fairly common problem referred to as sleep inertia. To a certain degree we all suffer from it & when our bodies are awake but our minds are still half asleep. But for young ones it can be very scary and even painful. The best thing to do is to just quietly comfort until the child fully wakes up (usually within 15-30 minutes). And most kids outgrow this in their toddler years. Other reasons can be anxiety- a child can be anxious about potty training or a new sibling who seems to be taking up a lot of parent time and attention. Check the room temperature and that your child's sleep clothing is appropriate and fits comfortably. Ear infections are painful and can cause a toddler to wake screaming in pain too. Check for signs of fever and other indications of illness, such as congestion or complaints of pain or discomfort.

There are many reasons for crying. Is it becos his diapers is wet/soiled? Hungry? Thirsty? Discomfort due to the environment, ie: is the room bed too hot / cold? Noisy environment? Or it could also be he just wants you to cuddle.. sometimes when a baby wakes up & realises that no one is around him, esp mummy, he may cry.

It is pretty normal for a 20-month old toddler as he is going into sleep regression again after the 4 months and 9 months regression phrases. It is a developmental milestone for your little one that his brain is still actively processing the new things that he learns even though when he is sleeping. Or might be he is experiencing teething of his canine teeth, axiety of separation or potty training. Try to comfort him while still leaving him in his crib. You can pat him, talk to him and give him a hug. Sit beside him till he is fully awake or drowsily going back to sleep. It is tough to go through these regession phases but it will be over in a few weeks' time. Monitor baby's body temperature and consult a doctor if you are in doubt whether there is any other medical ailments such as ear infection.

it could be teething pain or due to hot weather, mine is usually these two, else it may due to when he wakes up, he can't see you if you are the one who accompany him to sleep initially. :)