The name positive occipital sharp transients of sleep (POSTS) aptly communicates this pattern’s features. These transients first occur in late stage 1 non-rapid eye movement (NREM) sleep (deep drowsiness) and may persist into slow wave sleep. They are most frequent during the first 30 minutes after sleep onset, and the occurrence of POSTS in REM sleep is rare. Their waveform has a characteristic positive polarity sharp wave with phase reversal almost always at either the O1 or O2 electrode. They may be either monophasic or diphasic and have a triangular shape with symmetric rising and falling phases. When they are diphasic, the positive peak is prominent and followed by a negative potential of lower amplitude. The field usually extends across the bilateral occiput and is asymmetric in about one-third of EEG recordings (Rey et al., 2009). An amplitude asymmetry of up to 60% is common, and the total amplitude usually is between 20 and 75 μV and may be as high as 120 μV (Erwin et al., 1984; Vignaendra et al., 1974). The total wave duration typically is 80 to 200 milliseconds. POSTS may occur as individual transients, recurring without periodicity and with a separation of more than 1 second. Just as often, they occur in trains of up to four to six POSTS per second. The trains typically last about a second and rarely last more than 2 seconds (Mizrahi, 1996). POSTS rarely occur before the age of 3 years and are typically poorly formed in young children. They are most common from adolescence through middle adulthood and become uncommon after 70 years (Wright and Gilmore, 1985). Overall, they are a common finding; the EEGs of about 50% to 94% of healthy adults demonstrate POSTS if adequate sleep is recorded (Brenner et al., 1978; Egawa et al., 1983).