The sense of smell is the oldest of all the senses, because even single-celled organisms have sensors for chemical stimuli and respond to them. It is assumed that the brain region responsible for long-term memory evolved from the original olfactory brain. It has therefore also been investigated whether memory can be stimulated by scents, and at the end of a six-month experimental phase with subjects who had been stimulated with scents at night, it was shown that memory had improved, with them performing significantly better than at the beginning of the study, especially in classical linguistic memory tests in which they were asked to remember words. Images from functional magnetic resonance imaging also showed that the left uncinate fasciculus was more efficient and permeable after overnight exposure to scent. This branch of the net vein is important for processing speech, but is also involved in the retrieval of memory content. However, not only adults and the elderly benefit from nocturnal scent baths, but also children who sniffed rose scent while learning vocabulary and during the following night, because they remembered what they had learned better in later tests, and especially if the floral scent was also applied during exams. The influence on the brain can also be attributed in part to improved sleep, because learned material is processed further during sleep and stored in long-term memory. Studies in the sleep laboratory have shown that olfactory stimulation during sleep improves deep sleep and thus the most restful part of the sleep cycle.