Expected Nocturnal Blood Pressure for a Patient with Daytime BP of 114/72 mmHg
For a patient with an average daytime blood pressure of 114/72 mmHg, the expected overnight blood pressure would be approximately 100-102/60-62 mmHg, representing a 10-20% reduction from daytime values.
Physiologic Nocturnal Blood Pressure Decline
Blood pressure normally follows a circadian pattern with a predictable decline during sleep hours 1. The expected physiologic response includes:
- Normal "dippers" experience a ≥10% reduction in blood pressure from day to night 2
- Typical reductions range from 10-20% for systolic blood pressure and somewhat less for diastolic blood pressure 2
- The night/day pressure ratio averages 0.87 for systolic and 0.83 for diastolic pressure 1
Calculating Expected Overnight Values
Using the established physiologic patterns, for a daytime BP of 114/72 mmHg:
Systolic Blood Pressure:
- 10% reduction: 114 - 11.4 = 102.6 mmHg
- 13% reduction (average from meta-analysis): 114 - 14.8 = 99.2 mmHg
- Expected range: 99-103 mmHg 1
Diastolic Blood Pressure:
- 10% reduction: 72 - 7.2 = 64.8 mmHg
- 17% reduction (average from meta-analysis): 72 - 12.2 = 59.8 mmHg
- Expected range: 60-65 mmHg 1
Guideline-Based Thresholds
The established normative data from ambulatory blood pressure monitoring studies provides additional context 1:
- In normotensive subjects, average nighttime pressure is 106/64 mmHg (range 86-127/48-79 mmHg) 1
- For comparison, daytime pressure averages 122/77 mmHg in normotensive individuals 1
- The 2024 ESC guidelines define normal nighttime BP as <110/60 mmHg 1
Clinical Significance of Dipping Pattern
The magnitude of nocturnal blood pressure decline has important prognostic implications:
- Individuals maintaining ≥10% nocturnal reduction ("dippers") have lower cardiovascular risk 2
- "Non-dippers" who fail to achieve 10% reduction face significantly increased cardiovascular risk 2
- Nighttime blood pressure may be the best independent predictor of cardiovascular risk, even more than daytime values 2
Important Caveats
Several factors can affect the accuracy of nocturnal blood pressure assessment:
- Nocturnal urination can artificially elevate nighttime blood pressure means and obscure normal dipping patterns 3
- When patients wake to urinate, the prevalence of systolic non-dipping can be overestimated by 10-25% if these awake periods are included in nighttime averages 3
- At least 70% of blood pressure readings during nighttime periods must be satisfactory for valid interpretation 1
- Preferably, seven nocturnal readings should be obtained for accurate assessment 1