Discipline Equals Freedom Field Manual by Jocko Willink ( PDFDrive.com )

SLEEP
Sleep is a necessity. Humans need sleep. Failure to
get enough sleep has serious side effects. Lack of
sleep can cause negative hormonal changes, interfere
with the metabolizing of glucose, increase blood
pressure, and suppress the immune system. Less sleep
also means less human growth hormone in your body,
which means less muscle mass and weaker bones.
Mentally, the brain is impacted as the ability to pay
attention and concentrate begins to diminish and
problem solving and basic reasoning become less
acute. Furthermore, over an extended period, there
are psychological effects like paranoia and even
hallucinations.
But how much sleep is enough? Different people need
different amounts of sleep. Newborns can sleep up to
seventeen hours a day; toddlers can sleep up to
twelve hours a day. As people grow older, less sleep
is required. Teens generally need eight to ten hours
and by the time people are full adults eight hours
becomes the standard—though the actual number is
between seven and nine hours, depending on the
individual. Some people genetically need even less
sleep than that, but those people are rare. I am one
of those people.
But it isn’t only genetics.
You can also sleep less and fall asleep faster if you
are in good physical condition, eating clean, and