Blood pressure fluctuations can be the result of natural variations due to individual circadian rhythms, hypertension, stress, food sensitivities and use of certain illegal drugs, reports the Los Angeles Times. Consuming alcohol, experiencing emotional distress, being in a warm environment and stopping exercise can also cause fluctuations in blood pressure.
Humans experience a natural rise and fall in blood pressure throughout the day, explains the Los Angeles Times. Most people have lower blood pressure in the morning, with pressure at its highest in the afternoon.
Hypertension is the most common cause of blood pressure fluctuations, according to the Los Angeles Times. People with chronic high blood pressure often experience significant degrees of variation in blood pressure, as the blood vessels are more reactive and tighten more readily than those in people without hypertension.
Anxiety and other stressful emotional experiences, certain food sensitivities and the use of illegal street drugs can all cause a person's blood pressure to suddenly increase, notes the Los Angeles Times. If someone with a food sensitivity to salt eats a large amount of salt, then her blood pressure is likely to rapidly increase. Similarly, using drugs such as cocaine and methamphetamine causes a blood pressure spike.