Men who sleep 5 hours a night have significantly smaller testicles and a level of testosterone of someone 10 years older. Women have equivalent problems in reproductive health caused by lack of sleep.
Sleep deprived students learned 40% less. Good sleep stores recent memories for the long term and makes space for new memories.
Deep sleep gets worse with aging and this might contribute to cognitive decline.
Later school starting times increased SAT score of top 10% students by ~200 points from ~1300 to ~1500. And also increased their life expectancy, in part due to reducing car accidents by up to 70%.
Sleep deprived people had 60% more activity in the Amygdala (unregulated emotions).
One week of short sleep disrupts blood sugar levels to the point of making you pre-diabetic.
Reducing 1 hour of sleep increases heart attacks by 24%, whereas increasing 1 hour reduces heart attacks by 21%. This happens every year due to daylight saving time.
Reducing 4 hours of sleep decreases natural killer cells (which prevent cancer) by 75%.
Lack of sleep is strongly linked with multiple forms of cancer. Night-time shift work has been classified as a probable carcinogen by the World Health Association.
Short sleep predicts shorter life and all cause mortality.
Disrupted sleep increased cancer growth by 200% on mice.
Sleeping 6 hours reduced expression of genes related to immune function, and increased expression of genes related to tumor promoting, inflammation and cardiovascular disease.
Sleep is not an optional, life-style luxury. Sleep is a non-negotiable, biological necessity.