Blood pressure is a measurement of the force of blood against the walls of the arteries. Systolic blood pressure measures blood pressure when the heart is contracting, and diastolic blood pressure measures blood pressure when the heart muscle is relaxed. Systolic is the top number in a blood presssure reading, diastolic is the bottom one. Several blood pressure fluctuation causes bring changes in blood pressure levels.
Circadian Rhythm
Blood pressure naturally fluctuates throughout the day, following an individual's circadian rhythm. Circadian rhythm is the cycle of physiological, behavioral and biochemical processes in humans. Blood pressure is usually at its lowest in the morning and peaks in mid-afternoon. According to Dr. Joshua Penn from Cedars-Sinai Medical Group, blood pressure can fluctuate 10 to 15 mm of mercury on the systolic value and 5 to 10 mm of mercury on the diastolic value due to this natural body rhythm.
Hypertension
One of the most common causes of blood pressure fluctuation is hypertension, which is also known as high blood pressure. One high blood pressure reading does not mean an individual has hypertension. Hypertension is diagnosed after several high blood pressure readings. Normal blood pressure is considered 120/80 mm of mercury. Blood pressure can fluctuate significantly if someone has hypertension that is untreated or cannot be controlled.
Stress
When someone faces a stressful situation, the body prepares to deal with the situation by increasing heart rate, blood sugar, blood pressure and respiration rate. The peripheral arteries become constricted, which makes the heart work harder to pump oxygenated blood to the tissues of the body. Occasional stress is not usually harmful, but prolonged periods of stress can result in blood pressure fluctuations that occur on a regular basis.
Food Sensitivities
Food sensitivities can trigger blood pressure fluctuations after a trigger food has been ingested. If someone with a sensitivity to salt ingests a salty meal, blood pressure may increase temporarily. If these fluctuations do not occur frequently, they are usually not a cause for concern. If these fluctuations occur on a regular basis, dietary adjustments may be needed to prevent blood pressure surges related to food sensitivities.
Drugs
Drugs that cause the blood vessels to constrict can cause blood pressure fluctuations. Prescription and over the counter drugs such as acetaminophen, decongestants, birth control pills, antidepressants, immunosuppressants, non-steroidal anti-inflammatory drugs and stimulant medications used to treat attention-deficit hyperactivity disorder can cause blood pressure to become elevated. Illegal drugs such as cocaine and methamphetamine can also cause dangerous blood pressure fluctuations.
Caffeine
Caffeine is a stimulant that can cause temporary increases in blood pressure. According to Dr. Sheldon G. Sheps from the Mayo Clinic, two to three cups of coffee can cause systolic pressure to increase by 3 to 14 mm of mercury and diastolic pressure to increase by 4 to 13 mm of mercury. In people who do not drink caffeine regularly, the rise in blood pressure may be even greater. The cause for this spike in blood pressure is not known, but scientists suggest that caffeine causes the blood vessels to constrict.
