Consciousness refers to our awareness of ourselves and our environment, which varies depending on our attention. While conscious attention is focused on tasks, unconscious processes still occur. Daydreaming and fantasizing are common and may serve purposes like preparation, creativity, and stress relief. Biological rhythms like our circadian rhythm regulate sleep-wake cycles, with individuals varying as morning or evening types. Sleep occurs in stages including light, deep, and REM sleep, each with different brain wave patterns. Sleep serves functions like restoration and growth, and disorders can disrupt these functions.