Sleep, Rhythms, and Split-Brain Research
Your body runs on natural biological rhythms that control when you sleep, wake, and even when certain hormones are released. Circadian rhythms follow a roughly 24-hour cycle, controlled by your brain's internal clock in the suprachiasmatic nucleus (SCN).
Sleep stages cycle every 90 minutes throughout the night. You move through light sleep stages1−2, deep sleep stages3−4, and REM sleep where most vivid dreaming occurs. Your brain literally paralyses your body during REM to stop you acting out dreams!
Split-brain research by Sperry revealed how your brain's hemispheres specialise differently. When the connection between hemispheres is cut, patients can't verbally describe objects shown to their right hemisphere because language is processed in the left hemisphere. However, they can draw or point to these objects, showing the right hemisphere excels at visual-spatial tasks.
Study Tip: Ultradian rhythms (like sleep cycles) occur multiple times per day, while infradian rhythms (like menstrual cycles) take longer than 24 hours to complete.