Courtney is a participant in a laboratory sleep study. her eeg begins showing small bursts of electrical activity known as sleep spindles. courtney has entered sleep.

Courtney has entered STAGE 2 SLEEP.
There are two types of sleep, REM and NON REM SLEEP. The NON REM sleep is divided into three stages, which are stages 1, 2 and 3. The stage 2 of the NON REM sleep is the most prominent sleep stage. At this stage, the EGG usually show small burst of electrical activity which is called sleep spindle.

many animals include both aquatic and terrestrial species