7–9 hours of sleep
Short sleep raises blood pressure and inflammatory markers. The intervention is sleeping in this window, regularly.
Order of magnitude
Seven to nine hours a night, at a regular time.
The blood-pressure evidence is interventional and quite strong, but the largest effect - sleep extension - rests on 242 participants across seven studies with high heterogeneity, and the population studied was people with poor sleep to begin with.
Effects in detail
Each row is a directed edge from our database, with range, latency, evidence grade and the condition under which it applies at all.
| Marker | Effect | Latency | Mode of action | Outcome | Evidence | Condition | Sources |
|---|---|---|---|---|---|---|---|
| Diastolic blood pressure | helps. Lowers -2.90 mmHg confidence interval of the estimate, not the range one person can expect Twelve randomised trials in 688 adults with poor sleep give a systolic reduction of 4.91 mmHg (95 % CI 2.38 to 7.43); combining randomised and non-randomised studies gives 5.02 mmHg systolic and 2.90 diastolic. Grade B despite being a meta-analysis of randomised trials: heterogeneity is high (I2 74 % systolic, 88 % diastolic), the diastolic estimate mixes randomised with non-randomised studies, and the headline sleep-extension effect rests on 242 participants. | not specified | chronic | unclear | Evidence grade B | applies regardless of the starting value | |
| Systolic blood pressure | helps. Lowers -4.91 mmHg confidence interval of the estimate, not the range one person can expect Twelve randomised trials in 688 adults with poor sleep give a systolic reduction of 4.91 mmHg (95 % CI 2.38 to 7.43); combining randomised and non-randomised studies gives 5.02 mmHg systolic and 2.90 diastolic. Grade B despite being a meta-analysis of randomised trials: heterogeneity is high (I2 74 % systolic, 88 % diastolic), the diastolic estimate mixes randomised with non-randomised studies, and the headline sleep-extension effect rests on 242 participants. | not specified | chronic | unclear | Evidence grade B | applies regardless of the starting value | |
| HbA1c | helps. Lowers Direction known, size not established A meta-analysis of 20 observational studies in people with type 2 diabetes found higher HbA1c with both short and long sleep and with poor sleep quality. No effect size is entered despite the numbers being available, because they describe an association in cross-sectional and cohort data, not the effect of changing sleep. | not specified | chronic | unclear | Evidence grade C | applies regardless of the starting value |
What this measure costs
Counteracting effects of the same measure.
No counteracting effect is on file for this measure. That does not mean there is none, only that we found no defensible edge.
Moves without implying progress
Informational or no established effect: the marker moves or was checked, and that is not progress.
| Marker | Effect | Latency | Mode of action | Outcome | Evidence | Condition | Sources |
|---|---|---|---|---|---|---|---|
| high-sensitivity CRP | moves, and does not count. Lowers Direction known, size not established In 72 studies with more than 50,000 people, sleep disturbance was associated with higher CRP (effect size 0.12, 95 % CI 0.05 to 0.19), shorter sleep with higher CRP (0.09, 0.01 to 0.17) and the extreme of long sleep with higher CRP (0.17, 0.01 to 0.34). Grade C. | not specified | chronic | unclear | Evidence grade C | applies regardless of the starting value |
Sources
Full details of every study the rows above rely on.
Sleep Disturbance, Sleep Duration, and Inflammation: A Systematic Review and Meta-Analysis of Cohort Studies and Experimental Sleep Deprivation
Irwin et al. · Biological Psychiatry · 2016 · Cohort study
Effect of behavioural sleep interventions on blood pressure, heart rate, and heart rate variability in adults with poor sleep health: a systematic review, meta-analysis, and meta-regression analysis
Mostafa et al. · European Heart Journal Open · 2026 · Meta-analysis
The impact of sleep amount and sleep quality on glycemic control in type 2 diabetes: a systematic review and meta-analysis
Lee et al. · Sleep Medicine Reviews · 2017 · Review