The basic neuroscience of sleep

Sleep is something that we all do every night. And it was once thought that it was a period of time in which the brain and the body shut down completely. However, we now know that this is in fact, not the case, and that there are many changes in the brain and in our bodies physiology throughout the night while we are asleep. And also that sleep certainly does not represent a state of inactivity for the brain. Indeed, the brain goes through characteristic changes as we fall asleep, and then as asleep continues throughout the night. In 1929, Hans Berger the discovered electroencephalogram, or EEG, which is the tool we use to measure brain activity by placing electrodes on the scalp.

The EEG was later used in conjunction with electrodes that measure eye movements, or the electrooculargram, and muscle tone or the electromyogram to discover the dramatic changes in brain activity and physiology that occur throughout a night of sleep, revealing that there are two main types of sleep that occur in cycles. The following sections will discuss the basic neurophysiology of sleep, and how this differs at different stages of development until adult hood.