when you were first born because you kept on waking up for food
9-12. These ages are the growing years and lack of sleep can cause all sorts of problems including lack of growth.
I think you mean why should a 13 year old should go to sleep. If you do, then its important because without sleep your brain doesn't function properly because of lack of rest.
1969
1985
1902
in 2010 hehe
It is believed this was about 96AD.
New Years day
Lack of sleep for anyone makes them stress out more. They could fall asleep during the day and feel very frustrated. They might become very irritable and distant. Let them get as much sleep as possible on the weekend.
Most of the changes of puberty and the subseuent increases in height etc occur while you are asleep so it is recommended that at puberty you should have at least 8 hours uninterupted sleep.
if you mean how many hours you should sleep in a year it would be 3,650 hours of sleep for a regular year not a leap year
I got my industrial about 1 year ago. The first 6 months trying to sleep on it were sore. Now 1 year later and yes, I can sleep on it but in the morning it is still sore.