Blood pressure throughout the day
Up, then lower, then rising again and so on anyone who measures their blood pressure several times a day will soon notice that its not a fixed number that always stays the same.
Blood pressure follows natural fluctuations over the day. To prepare the body for getting up, blood pressure starts to rise before waking. The first real blood pressure peak is between 8 and 9 a.m. and this is often when the highest readings of the day are recorded. Around midday the blood pressure curve usually falls again, then rises to a second peak in the late afternoon between 4:00 and 6:00 p.m. The lowest values are normally measured at night this is the socalled nighttime drop. This drop is often missing in secondary forms of hypertension and can therefore provide a clue to the cause of high blood pressure. These fluctuations are called the circadian rhythm. Blood pressure follows this rhythm in people with normal blood pressure and in most people with hypertension. The rhythm is controlled by our autonomic nervous system the part of the nervous system that is largely beyond our voluntary control.
There are other normal blood pressure changes during the day that we can more or less control. For example, blood pressure rises in stressful situations and during physical exertion. This is a normal reaction. In healthy people the values fall back quickly to a normal level afterwards after exercise they often even drop slightly below preexercise levels. Thats why exercise is an important way to lower blood pressure.
So far, these daily blood pressure fluctuations are normal. But what happens if you have high blood pressure?
If high blood pressure is present, the normal fluctuations occur on a higher baseline. That means that starting from a higher base level, the fluctuations also happen at higher values, which can lead to critically elevated readings.
As already mentioned, the circadian rhythm is sometimes disturbed in people with high blood pressure. Values may not fall much at night or may even rise during the night. This can be detected with a 24hour blood pressure measurement.
An excessive rise in blood pressure in the morning socalled morning hypertension is also especially important. It is linked to a higher number of strokes, heart attacks and cases of sudden cardiac death during this time.
Our charts show in the first image (blue) the blood pressure pattern in a person with normal blood pressure. The values stay within the normal range. They rise with activity, then fall again and show a clear drop at night to the lowest level of the day.
The second plot (red) shows an example of a pattern with high blood pressure. The higher baseline and the missing nighttime dip are clearly visible. The morning blood pressure peak is clearly too high. The large difference between the systolic and diastolic readings also shows an increased pulse pressure.
The fall in blood pressure at night is called "dipping." If blood pressure falls by the normal amount about 1020% of the daytime average this is called "normal dipping." If the drop is less than 10% it is called "nondipping." "Reverse dipping" means blood pressure rises at night above daytime averages. A very large nighttime fall of more than 20% of the daytime average can also occur, especially in older people; this is called "extreme dipping."
Both a missing and an excessively large nighttime drop carry an increased risk and should be taken into account when diagnosing and prescribing treatment.
Sources:
- https://www.herzstiftung.de/herz-sprechstunde/alle-fragen/zusammenhang-tageszeit-und-blutdruck
- https://flexikon.doccheck.com/de/Dipping
- https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.115.06981
- https://www.aerzteblatt.de/nachrichten/105160/Langzeitstudie-bestaetigt-prognostische-Bedeutung-des-naechtlichen-Blutdrucks-bei-Hypertonie
This article comes from BloodPressureDB – the leading app since 2011 that helps hundreds of thousands monitor their blood pressure every day.
Our content is based on carefully researched, evidence-based data and is continuously updated (as of 10/2024).
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as in outpatient care, and has led BloodPressureDB's specialist editorial team since 2015. Thanks to her extensive additional qualifications as a paramedic, first responder and in various therapy and emergency areas, she provides solid, practical and reliably reviewed information.
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as in outpatient care, and has led BloodPressureDB's specialist editorial team since 2015. Thanks to her extensive additional qualifications as a paramedic, first responder and in various therapy and emergency areas, she provides solid, practical and reliably reviewed information.
