Nighttime used to be my worst time for increased high blood pressure and other health problems.
During the nighttime, almost all diseases and health problems get worse because of the body's natural changes to metabolism during the evening and night (ref:Circadian Rhythm).
High Blood Pressure and anxiety are caused, in part, by an imbalanced metabolism, <IN MY HONEST OPINION>. During the nighttime, an imbalanced metabolism can become that much worse due to night-time metabolism changes.
Improve one's metabolism and one can improve one's health and lessen night-time increases in symptoms.
Two relatively inexpensive and effective things that one can do to improve their metabolism are a very healthy diet and demanding, appropriate exercise. Personally, I cannot believe the significant improvements to my own health due to diet and exercise. I've been battling heart failure, Permanent Atrial Fibrillation, Chronically High Blood Pressure, among other nasty health problems, for over 20 years, and I am amazed at the improvements to my health due to exercise and diet.
Regards, and best of luck getting your blood pressure and anxiety problems under control!