Read watch paper on sleep use these sources

https://www.sleepfoundation.org/how-sleep-works/sleep-facts-statistics
https://www.sleepfoundation.org/
https://www.ninds.nih.gov/Disorders/patient-caregiver-education/Understanding-sleep
https://www.sleepfoundation.org/sleep-disorders
https://www.apa.org/topics/sleep/why