Three of them are doing just fine. However, one of them has a problem as evidenced by the leaves which look as if someone has held a candle too close to the edges of each leaf and they have become brown and crispy - covering almost half of the leaf, but starting with the outside edge (away from the stem).
Again infants and children normally drool during sleep, but some adults too drool during sleep. Moreover, drooling in case of adult is not always normal. Drooling can be quite common in adult while sleeping. But when awake, drooling in adult can not only be embarrassing but very uncomfortable leading to social and mental burden. The reasons for an adult to drool during sleep can be due to an open mouth, abnormal structure of the mouth like enlarged tonsils, large tongue or overcrowded teeth.
Biting the tongue while sleeping is not abnormal if it occurs once in a while. It is normal to accidentally bite your tongue while sleeping. However, if it becomes a frequent scenario, it is a problem that requires to be dealt with. There are several reasons that may be the cause of biting your tongue when in sleep. One of them is when your tongue is bigger than it should be. In this case, it is a frequent occurrence to accidentally bite it while eating or talking. There are other causes of the same other than disproportional size of the tongue.