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Blood pressure is the force exerted by the heart in pumping the blood through the arteries and the
resistance by the veins to this flow.
Blood pressure varies all the time, influenced by mental and physical factors and is
never constant.
In general, blood pressure is highest during the working hours and gradually decreases during the
afternoon and evening hours. It is low during sleep and increases at a relatively fast rate after arising
from bed.
Causes for Changes in Blood Pressure
• Body movement
• Conversation
• Mental Tension
• Nervousness
• Emotions
• Eating
• Drinking Alcohol
• Smoking
• Measurement posture
• Recent Urination or Bowel Movement
• Room temperature
• Changes in the surroundings such as movement or noise, etc.
Blood pressure measured at hospital or clinics tends to be higher than when it is
measured at one's home, this symptom is known as "White Coat Syndrome".
Being in a hospital could cause mental tension and therefore lead to higher blood pressure than that
taken under relaxed condition at one's own home.
Judgment such as a change of dosage of a drug based on measurement results should
not be made by patients on their own without professional consultation.
Blood pressure classification by WHO (1999)
180~
160~179
140~159
130~139
120~129
~120
mmHg
(severe)
(moderate)
(mild)
80
~
80
84
~
85
89
~
90
99
~
100
109
~
110
~
High Normal
Normal
DIA
SYS
Op
tim
al
Hyp
ert
ens
ion
20
40
60
80
100
120
140
160
180
200
12131415161718192021222324 1 2 3 4 5 6 7 8 9 1011
Blood pressure (mmHg)
Systolic
Diastolic
Time
Blood pressure changes shown below.
Upper arm blood pressure data
Tips on taking blood pressure