It is a common knowledge that most people need between 7 and 8 hours of sleep per night. however, sleep needs differ according to factors like age, gender, health, and lifestyle. sleep deprivation and various sleep disorders increase risk for diseases like cancer, obesity, diabetes and cardiovascular disease. generally, people who sleep better also live longer and experience better quality of life than those who get insufficient sleep or poor-quality sleep. in this activity, you will learn about what happens in your mind and body during rem versus nrem sleep.