Studies showed no correlation between stimulation and amount of sleep for children three years of age or older. The stimulation that babies receive helps them to develop intellectually. The babies who had a less stimulating routine gained weight at an average rate. Babies with less stimulating routines usually get extra sleep during the day.
A study comparing infant care revealed that the amount of stimulation babies receive affects their sleep. At six months of age, the babies in the study with a less stimulating daytime routine slept an average of two hours more per day than those with a more stimulating routine. Since sleep plays a very important role in a child' s development, parents would be wise to reduce the amount of stimulation their babies receive.
Which one of the following statements, if true, most seriously weakens the argument?