When we think of sleep, we think of giving
the body and mind a few hours a day to rest and
rejuvenate. We yearn for more hours of sleep because it gives us
the energy that we need to perform our daily activities. This is our
perception of sleep- temporarily turning off of our physical and mental
faculties at night so we can have an energy-filled day the next morning.
Several interesting findings were established
since scientists have found ways to measure brain activity. One of them is
the discovery that sleep consists of five different stages. By using
an electroencephalograph, doctors were able to identify that sleep is
divided into five different stages, each of which manifest a distinct set
of qualities. Further studies on human brain activity revealed that sleep
advances through stages as manifested by different sets of brain
wave patterns.
Stage 1
It should be noted that humans display two
general types of brain wave activity namely the Beta Wave and the Alpha
Wave. The former is most often detected when we are wide awake, while
the latter is present during the state of sleep.
Beta Waves are low amplitude, high-frequency
waves that lack synchrony compared to other types of brain wave patterns.
The desynchronous nature of Beta Waves is made apparent by the various
mental tasks that humans perform when wide awake.
On the other hand, Alpha Waves feature
synchrony as it shows that an individual is in a relaxed and restful state
of being. While the frequency of brain wave activity decreases, the
amplitude increases at the same time. It should be noted that Alpha Waves
are not only seen when a person is in deep slumber. There are
certain activities that can convert Beta
Waves into Alpha Waves like meditation and relaxation exercises.
Stage 2
The Theta Waves activity continues through
the second stageof sleep. The two defining characteristics observed during
Stage 2 is the appearance of K complexes and sleep spindles. There is a
sudden increase in both the frequency and amplitude of brain wave
activity in Stage 2. It is also during this stage that core body
temperature and heart rate begin to gradually decrease. It
may not even feel like you are already sleeping during the first two stages of
sleep as brain wave activity still hasn’t shifted completely from Beta to Alpha
Wave activity.
Stage 3 and Stage 4
Stages 3 and 4 of sleep are characterized by
the appearance of Delta Waves. It is during the third stage that we are
most likely to transition from light sleep to deep sleep. Delta Waves are
known to be highest in amplitude and lowest infrequency. There are no
distinguishing qualities that clearly separate the third and fourth stage
of sleep, except that there are more than 50% of Delta Waves during
Stage 4 sleep. We are most likely to feel disoriented and sleepy
when awakened during these sleep stages. In addition, sleep disorders
namely sleep walking, sleep talking, and bed wetting mostly occur during
Stage 3 or Stage 4 ofsleep.
Stage 5 or REM Sleep
As the name implies, REM sleep is
characterized by rapid eye movement and temporary paralysis of
skeletal muscles. The brain wave patterns during Stage 5 are a combination
of desynchornous Alpha and Beta Waves. It is during the fifth stage
of sleep when we are most likely dreaming. Paradoxical sleep is a
term associated with Stage 5 of sleep as brain activity and other bodily
functions increase while body movement is in a more relaxed and restful
state.
The Stage 5 of sleep only last for 15 minutes
during the first cycle of sleep. Once REM sleep ends, it goes back to
Stage 2 and so forth. During the second and succeeding cycles, Stages 2 to
4 become shorter while REM sleep progressively becomes longer in duration.
No comments:
Post a Comment