Every night, almost everyone on the planet
enters into a state of unconsciousness and paralysis.
But what is really happening inside the body
when we drift off?
And what's the impact if we don't get enough sleep?
Sleep is regulated by your circadian rhythm,
or body clock, located in the brain.
The body clock responds to light cues,
ramping up production of the hormone melatonin at night
and switching it off when it senses light.
There are four stages of sleep
that the body experiences in cycles throughout the night.
On a good night, we cycle through these stages
four or five times.
Stages one and two are light sleep.
This is a transition from being awake to falling asleep.
Heart rate and breathing begin to slow,
body temperature falls, and muscles may twitch.
Stage three is sometimes referred to as delta sleep
because of the slow delta brainwaves
that are released during this stage.
This is the first stage of deep sleep,
where our cells produce the most growth hormone
to service bones and muscles,
allowing the body to repair itself.
Stage four is where we begin to dream.
The body creates chemicals
that render it temporarily paralyzed
so that we do not act out our dreams.
In this stage, the brain is extremely active
and our eyes, although closed, dart back and forth
as if we were awake.
Humans roughly spend 1/3 of their lives asleep.
Modern lifestyles, stress,
and the proliferation of technology
mean that people are sleeping far less today
than they were a century ago.
Sleeping less than seven hours per day
is associated with an increased risk
of developing chronic conditions,
which could reduce life expectancy.
So for a healthier, longer life, get some shuteye.