Be able to explain the stages of sleep and what happens in each one. Also be able to share the reason sleep is so important in our lives.
The stages of sleep refer to distinctive changes in the electrical activity of the brain and accompanying physiological responses of the body that occur as you pass through different phases of sleep.
Stage 1 sleep: Transistion from wakefulness to sleep and lasts 1-7 minutes. In it, you gradually lost responsiveness to stimuli and experience drifting thoughts and images. Stage 1 is marked by the presence of theta waves, which are lower in amplitude and lower in frequency (4-7 cycels per second) than alpha waves.
Stage 2 Sleep: Marks the beginning of waht wwe know as sleep, since subjects who are awakened in stage 2 report having been asleep. EEG tracings show high-frequency bursts of brain activity called sleep spindles.
Stage 4 Sleep: Also called slow wave or delta sleep, is characterized by waves of very hight amplitude and very low frequency (less than 4 cycles per second) called delta waves. Stage 4 is often considered the deepest stage of sleep because it is the most difficult from which to be awakened. During stage 4, heart rate, respirations, temperature, and blood flow to the brain are reduced, and there is a marked secretion of GH (growth hormone), which controls levels of metabolism, physical growth, and brain development.