presentation on Sleep patterns of humans and their eeg pattern

useful for physiology students mbbs can read to make ppt

1. SLEEP Sleep is defined as unconsciousness from which the person can be aroused by sensory or other stimuli. It is to be distinguished from coma, which is unconsciousness from which the person cannot be aroused. There are multiple stages of sleep, from very light sleep to very deep sleep; sleep researchers also divide sleep into two entirely differ] ent types of sleep that have different qualities, as follows. TYPES OF SLEEP Sleep is of two types: 1.Rapid eye movement sleep or REM sleep or paradoxical sleep{25% of sleep} 2.Non-rapid eye movement sleep, NREM sleep or non-REM sleep{75% of sleep}

2. Non-REM Sleep As the individual goes to sleep, he advances from stage 1 to stage 4 of slow wave sleep. These are four stages of progressively deepening sleep Stage 1 First, subject becomes drowsy; the EEG shows a change from beta to alpha rhythm. Immediately, light sleep begins during which the alpha rhythm is replaced by high fre quency and low amplitude EEG waves. Stage 2 The subject then enters into stage 2 sleep. The ampli tude of EEG waves slightly increases in this sage. The hall marks of EEG pattern in stage 2 are sleep spindles and K-complexes. Sleep Spindles Sleep spindles are bursts of alpha like waves having fre quency of 12–14 Hz and amplitude of about 50 µV, each lasting for about two seconds. They are called sleep spin dles because of their characteristic waxing and waning amplitude.

3. K-Complexes K-complexes are high amplitude-sharp waves appearing irregularly in EEG. Stage 3 This is the stage of moderately deep sleep. The rhythm of the EEG waves shows lower frequency and higher amplitude. Stage 4 This is the stage of deep sleep, with delta rhythm pre dominant over the whole scalp. Maximum slowing (lowest frequency) with large amplitude waves is seen in this phase. It is very difficult to wake up the subject in this stage. In young adults, maximum time of sleep is spent in stage 4 REM Sleep After completion of slow wave sleep, a new pattern EEG waves starts suddenly. During this stage the slow waves are replaced by rapid low-voltage EEG activity. This is called paradoxical sleep, because the EEG activity is very rapid like β rhythm as seen in awakened state; still it is difficult to awaken the individual. In fact, threshold for arousal by sensory stimuli is raised during this stage. This phase lasts for about 10 to 15 minutes