direction or touch the infant every time the infant looks at them and babbles. It also helps if parents respond to what they think their baby is saying (for example, giving a ball or commenting when the baby looks at the ball and babbles). Responding to sounds produced when the baby looks at an object (object-directed vocalizations) thus provide an opportunity to learn the name of the object. In this way, babies also learn that sounds are associated with objects. However, language development is only achieved if parents react positively (e.g. smile) in response to the infant's babbling. A high response rate without a connection to the infant's utterances does not lead to language promotion. It is detrimental to language development if a mother instead tries to divert the infant's attention to something else. Sleep A 2018 review analysed 146 studies on infant sleep behavior and listed several factors that show an effect on sleep duration and the number of night wakings. For example, stimulating daytime activities, reading aloud before sleeping, early bedtime, a sleep routine, and avoiding television and media exposure before bedtime are associated with longer sleep duration and fewer nighttime awakenings. Furthermore, strong parental involvement at falling asleep is associated with shorter sleep duration, slower falling asleep and more frequent night-time awakenings in the studies analysed. Strong parental involvement is understood to include parental presence, cradling, or breastfeeding at bedtime, as well as carrying the infant to sleep and then putting the infant down. Strong parental involvement has a negative effect on infant sleep because the infant cannot develop the ability to self-soothe. On the other hand, low parental involvement at bedtime gives the infant room to learn self-soothing and self-regulation. In 2020, a Finnish study established (according to the research leader) for the first time a reference value for infant sleep quality based on a large data set (about 5,700 babies). Almost 40% of the participating parents with eight-month-old babies said they were worried about their sleep. In fact, sleep problems were common; however, children fall asleep faster, wake up less often during the night and stay awake less late at night the older they get. At the same time, total sleep time decreases. The study was also able to determine reference values for normal sleep (see table). Children who sleep significantly less than average would usually benefit from supportive measures, for which a number of