Librería Perelló (Valencia)
Librería Aciertas (Toledo)
El AlmaZen del Alquimista (Sevilla)
Librería Elías (Asturias)
Librería Kolima (Madrid)
Donde los libros
Librería Proteo (Málaga)
Sleep is an important biological process that is essential for our physical and mental health. It helps us to get energy, keep our brain healthy, and store memories. Sleep deprivation is linked to a number of health problems, including obesity, heart disease, diabetes, and psychological disorders. Sleep Stages Sleep stages can be divided into two main categories: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. During REM sleep, our eyes move rapidly, our muscles relax, and we dream. NREM sleep is divided into four stages: N1, N2, N3, and N1 Sleep N1 sleep is the lightest stage of sleep. It is characterized by a slowing of the heart rate and breathing, and a decrease in muscle tone. During N1 sleep, we may be aware of our surroundings and may be able to be easily awakened. N2 Sleep N2 sleep is a deeper stage of sleep than N1 sleep. It is characterized by even slower heart rate and breathing, and a further decrease in muscle tone. During N2 sleep, brain waves become slower and more regular. N3 Sleep N3 sleep is the deepest stage of sleep. It is characterized by very slow heart rate and breathing, and a marked decrease in muscle tone. During N3 sleep, brain waves are very slow and synchronized.
