Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
Francesca Canellas
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
Mourad Akaârir
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
José A. Rubiño
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
Pere Barceló
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
Aida Martín
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
Antoni Gamundí
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
M. Cristina Nicolau
Laboratori de Neurofisiologia del Son i dels Ritmes Biològics, Grup de Recerca Neurofisiologia del Son i Ritmes Biològics, Department of Biologia, Universitat de les Illes Balears, Ctra Valldemossa, km 7.5, 07122 Palma de Mallorca, Illes Balears, Spain
Mammals evolved from small-sized reptiles that developed endothermic metabolism. This allowed filling the nocturnal niche. They traded-off visual acuity for sensitivity but became defenseless against the dangerous daylight. To avoid such danger, they rested with closed eyes in lightproof burrows during light-time. This was the birth of the mammalian sleep, the main finding of this report. Improved audition and olfaction counterweighed the visual impairments and facilitated the cortical development. This process is called “The Nocturnal Evolutionary Bottleneck”. Pre-mammals were nocturnal until the Cretacic-Paleogene extinction of dinosaurs. Some early mammals returned to diurnal activity, and this allowed the high variability in sleeping patterns observed today. The traits of Waking Idleness are almost identical to those of behavioral sleep, including homeostatic regulation. This is another important finding of this report. In summary, behavioral sleep seems to be an upgrade of Waking Idleness Indeed, the trait that never fails to show is quiescence. We conclude that the main function of sleep consists in guaranteeing it during a part of the daily cycle.
