Acute stress triggers a surge of hormones that temporarily raise heart rate and blood pressure. These spikes are normal and settle once the stressor passes. The question of whether long-term stress directly causes permanent hypertension is debated, but chronic stress is clearly linked to higher pressure, partly through behaviours it encourages such as poor sleep, smoking, drinking, comfort eating and inactivity.
Stress can also produce 'white coat' readings, where pressure is high at the clinic but normal at home. This is why home or 24-hour monitoring is often used to confirm a diagnosis.
Managing stress through exercise, sleep, relaxation techniques and social support is worthwhile for overall heart health. If your readings stay high despite this, see a doctor, as stress is rarely the sole cause and other factors may need treatment.