A reading of 108/68 mmHg falls squarely in what every major medical guideline considers normal, healthy blood pressure. It is not low in a clinical sense, and for most people it represents the kind of reading that cardiologists are happy to see. The more interesting question is why so many people worry about readings in this range, and what circumstances, if any, could make a number like 108/68 worth a closer look.
Where 108/68 Sits on the Spectrum
Current guidelines from the American Heart Association and the American College of Cardiology define normal blood pressure as a systolic (top number) below 120 mmHg and a diastolic (bottom number) below 80 mmHg. A reading of 108/68 clears both thresholds comfortably. It is not borderline. It is not “low normal.” It is simply normal. The elevated category does not begin until systolic reaches 120, and stage 1 hypertension starts at 130/80. By those standards, 108/68 gives you substantial breathing room.
There is no universally agreed-upon cutoff for when blood pressure is “too low.” Hypotension is sometimes loosely defined as systolic below 90 or diastolic below 60, but those numbers are guidelines of convenience, not biological thresholds. At 108 systolic and 68 diastolic, you are well above both of those markers. The gap between your reading and even the loosest definition of low blood pressure is wide enough that, on numbers alone, there is nothing to flag.
Why the Number Alone Does Not Tell the Whole Story
Blood pressure is one of those measurements where context matters as much as the digits. A person who has always run around 108/68 and feels fine is in a different situation from someone whose pressure just dropped from 140/90 to 108/68 over a few weeks. The first scenario is unremarkable. The second might reflect a medication adjustment, dehydration, or an underlying change that needs attention.
What clinicians care about, far more than any single reading, is whether you have symptoms. Low blood pressure only becomes a medical concern when it causes problems like dizziness, fainting, blurred vision, nausea, or an inability to concentrate. If you feel well at 108/68, the reading is doing exactly what a healthy cardiovascular system should do: delivering blood to your organs without pushing harder than necessary. The absence of symptoms at this level is, by itself, the most reassuring piece of data you can have.
The J-Curve Debate
One reason people worry about readings in the low-normal range is that researchers have spent decades arguing about whether there is a floor below which blood pressure starts to cause harm. This is the so-called J-curve: the idea that cardiovascular risk is not a straight line where lower is always better, but a U- or J-shaped curve with a sweet spot somewhere in the middle.
A large study of more than one million Korean adults found that the lowest risk for vascular death occurred at a systolic pressure around 100 mmHg. Below that, risk crept back up, and people with systolic readings under 90 had meaningfully higher rates of death from ischemic heart disease.1PubMed. Low Systolic Blood Pressure and Vascular Mortality Among More Than 1 Million Korean Adults At 108 systolic, you are above that inflection point. The J-curve, to the extent it exists, does not touch you.
The diastolic side has its own version of this concern. Because the heart’s coronary arteries fill with blood primarily during the diastolic phase of each heartbeat, very low diastolic pressure can theoretically starve the heart muscle of blood flow. This matters most for people who already have blocked coronary arteries or thickened heart walls, since those conditions narrow the margin of safety for coronary perfusion.2PubMed Central. The Diastolic Blood Pressure J-Curve in Hypertension Management: Links and Risk for Cardiovascular Disease Early work on the diastolic J-curve identified the lowest-risk zone as somewhere around 85 to 90 mmHg in patients being treated for hypertension.3PubMed. Coronary flow reserve and the J curve relation between diastolic blood pressure and myocardial infarction But that research focused on people with existing high blood pressure and coronary artery disease, not on healthy individuals who naturally sit at 68 diastolic.
A study of patients who already had confirmed vascular disease found J-curve-shaped outcomes, but the nadir in that population was around 143/82, which is far above what most people consider low.4PubMed. Relation between blood pressure and vascular events and mortality in patients with manifest vascular disease: J-curve revisited The broader debate about whether low diastolic pressure causes harm or simply reflects underlying illness remains unresolved. Proponents of the causal theory point to reduced coronary perfusion, while skeptics argue that low blood pressure in sick patients is a marker of poor health rather than a cause of it.5American Heart Journal Plus: Cardiology Research and Practice. The diastolic blood pressure J-curve revisited: An update Data from elderly populations mirrors this: a U-shaped mortality curve appeared when systolic pressure dipped below 120, but that excess risk was concentrated among people who already had cardiovascular disease, not among otherwise healthy individuals with naturally low readings.6PubMed. Blood pressure and cardiovascular morbidity and mortality rates in the elderly
The takeaway for someone sitting at 108/68 without heart disease is straightforward: the J-curve research does not apply to you. It is a concern for people with existing coronary blockages whose blood pressure is being pushed down by medications, not for people whose bodies naturally land in the low-normal range.
Your Reading Might Be Different Than You Think
Before spending too much energy interpreting any single blood pressure number, it is worth appreciating how much that number can shift depending on how and when it was taken. Blood pressure is not a fixed constant. It fluctuates throughout the day, in response to stress, posture, caffeine, conversation, a full bladder, and even the act of being in a medical setting.
The so-called white-coat effect is well documented. A study of home versus office readings found that about 78% of people had higher systolic blood pressure in the doctor’s office than at home.7PubMed. Home blood pressure: variability, comparison with office readings and proposal for reference values If your 108/68 was taken in a clinic, your resting pressure at home could be even lower. If it was taken at home, it is probably a more accurate reflection of your true baseline. In older adults, the gap between office and home readings can vary with overall health; frailer individuals sometimes show the opposite pattern, with home readings actually exceeding office readings.8PubMed Central. Office and home blood pressure and their difference according to frailty status among community-dwelling older adults: the NOSE study
Equipment matters too. A randomized trial found that using a regular-size blood pressure cuff on someone who actually needed a small cuff produced a systolic reading that was, on average, about 3.6 mmHg too low.9PubMed Central. Effects of Cuff Size on the Accuracy of Blood Pressure Readings: The Cuff(SZ) Randomized Crossover Trial The error runs the other direction if you use a cuff that is too small for your arm. Either way, a mismatched cuff can nudge a reading by several points in either direction, which is enough to push a true 112/70 reading down to 108/68 or vice versa. If you are measuring at home, make sure the cuff fits your upper arm properly.
Blood pressure also follows a circadian rhythm. It naturally dips by roughly 10 to 20 percent during sleep compared to daytime levels.10PubMed Central. Blunted nocturnal decline in blood pressure If you measured 108/68 first thing in the morning, before your body has fully ramped up, you are catching yourself near the bottom of that daily cycle. A mid-afternoon reading might come back a few points higher.
Situations That Temporarily Push Blood Pressure Down
Several common life circumstances can temporarily lower blood pressure into ranges that feel unfamiliar, even if they are medically benign.
Pregnancy is one of the most dramatic. Blood pressure drops early in pregnancy because blood vessels relax and cardiac output increases to support the developing fetus.11American Journal of Obstetrics and Gynecology. Early pregnancy changes in hemodynamics and volume homeostasis are consecutive adjustments triggered by a primary fall in systemic vascular tone The pattern typically shows a dip in the first and second trimesters before blood pressure gradually returns to pre-pregnancy levels later on.12PubMed Central. Trajectory of blood pressure change during pregnancy and the role of pre-gravid blood pressure: a functional data analysis approach A reading of 108/68 during the second trimester, for someone who usually runs around 118/75, is a perfectly expected and healthy shift.
Dehydration is another common cause. When you are behind on fluids, the total volume of blood circulating through your system drops, and pressure follows. Endurance athletes who have been sweating heavily, people recovering from a stomach bug, and anyone who simply forgets to drink water on a hot day can see their blood pressure dip below where it usually sits.
Medications are a frequent culprit in more pronounced drops. Many drugs prescribed for heart disease, mental health conditions, and prostate problems can interfere with the body’s ability to maintain blood pressure when you stand up. A review of drug-related blood pressure drops found that numerous cardiovascular and psychoactive medications affect the standing blood pressure response, and that this risk increases when medications overlap with other predisposing factors like advanced age or existing neurological conditions.13PubMed Central. Drug-Related Orthostatic Hypotension: Beyond Anti-Hypertensive Medications If you have recently started or changed a medication and your blood pressure has fallen noticeably, a medication review with your provider is a reasonable step.
Orthostatic Hypotension and the Standing-Up Problem
Even if your seated blood pressure is a perfectly healthy 108/68, you could still experience problematic drops when you stand up. This is called orthostatic hypotension, and it is one of the most common reasons people feel dizzy or lightheaded despite having fine baseline numbers. It reflects a failure of the reflexes that normally tighten blood vessels and speed up the heart in the moment you go from sitting or lying down to standing.
Orthostatic hypotension is considered a sign of dysfunction in the autonomic nervous system and can be caused or worsened by a range of conditions from diabetes to Parkinson’s disease.14PubMed Central. Orthostatic hypotension: From pathophysiology to clinical applications and therapeutic considerations The dizziness or vertigo associated with it appears to result from reduced blood flow to the brain during the momentary pressure drop.15PubMed. Orthostatic hemodynamics in the vertebral artery and blood pressure in patients with orthostatic dizziness/vertigo
For someone who already sits at the lower end of normal, there is less of a buffer before a standing-induced drop crosses into symptomatic territory. If you notice that you feel fine while seated but get lightheaded every time you stand up quickly, the issue probably is not your baseline reading of 108/68 itself, but rather how your body manages the transition. Simple strategies help: stand up slowly, stay hydrated, and avoid prolonged standing in hot environments. If the episodes are frequent or severe, that is worth bringing to a doctor’s attention, since the underlying cause often responds well to targeted management.
When Low Blood Pressure Should Actually Worry You
There is a meaningful difference between habitually low blood pressure in a healthy person and a blood pressure that is low because something is going wrong. The former is benign. The latter can be dangerous.
Sepsis, severe bleeding, major allergic reactions, and heart failure can all cause blood pressure to plummet. In those cases, the drop is a sign of a medical emergency, not a quirk of physiology. Similarly, aggressively lowering blood pressure with medications in someone who has compromised blood flow to the brain can trigger ischemic events. Case reports have documented patients developing new or worsened stroke symptoms after even modest medication-driven blood pressure reductions, especially in the setting of acute stroke or transient ischemic attack.16PubMed. Stroke precipitated by moderate blood pressure reduction
None of this is relevant to an otherwise healthy person who sees 108/68 on their home monitor. The danger zone for low blood pressure is defined by symptoms, acuity, and context, not by a number on its own. A person who always runs at 105/65, feels great, and has no underlying disease is not at risk. A person whose blood pressure is 105/65 because they are bleeding internally is in serious trouble. The number is the same; the meaning is completely different.
What Indigenous Populations Reveal About “Natural” Blood Pressure
One of the more fascinating pieces of context for understanding a reading like 108/68 comes from studies of indigenous populations living traditional lifestyles. Research on the Yanomami people of southern Venezuela found that their blood pressure averaged around 95/63, a reading that would alarm many people accustomed to Western norms. Even more striking, their blood pressure stayed at roughly that level from childhood through old age, with no upward trend over the decades. The age-related rise in blood pressure that Western societies treat as normal does not appear to be biologically inevitable. Research in native Papuan populations similarly found no age-related increase in systolic blood pressure, a pattern attributed at least partly to lifelong diets low in sodium and high in potassium.17PubMed. Arterial stiffness, not systolic blood pressure, increases with age in native Papuan populations
High sodium intake is linked to elevated blood pressure through several mechanisms, including water retention, increased resistance in peripheral blood vessels, and changes to blood vessel function and autonomic nervous system activity.18PubMed Central. Sodium Intake and Hypertension The populations that eat very little sodium and maintain lifelong blood pressures in the range of 95/63 are not suffering for it. They have extremely low rates of hypertension and cardiovascular disease. Seen through that lens, 108/68 in a modern, salt-consuming society is not “low.” It is closer to what human blood pressure looks like when it has not been pushed upward by modern dietary patterns.
The Nighttime Dip and 24-Hour Blood Pressure Patterns
If you are someone who tracks blood pressure throughout the day, you may notice that your readings vary considerably. That variation is not noise; it reflects real physiological rhythms that clinicians have started paying closer attention to. A healthy person’s blood pressure dips during sleep and rises in the early morning hours as the body transitions from rest to activity. People whose blood pressure does not dip by at least 10% at night, sometimes called nondippers, face somewhat worse cardiovascular outcomes, although the pattern’s predictive power is modest once you account for overall 24-hour blood pressure levels.19PubMed. Predictive role of the nighttime blood pressure The nondipping pattern reflects a disruption in the normal circadian blood pressure rhythm and has been linked to changes in the autonomic nervous system and the kidneys’ handling of sodium.20PubMed. Pathophysiology of the Nondipping Blood Pressure Pattern
For someone with a daytime reading of 108/68, a normal nighttime dip would bring the numbers down to roughly the mid-90s over the upper 50s during sleep. That is completely fine. If your daytime number is 108/68 and your nighttime number is also 108/68, that absence of a dip might deserve a conversation with a doctor, not because of the number itself, but because of what the missing rhythm could signal about autonomic function or kidney health. Most people never need this level of monitoring, but it is worth knowing about if you use a device that tracks blood pressure overnight.
Athletic Hearts and Naturally Low Readings
Regular aerobic exercise tends to lower resting blood pressure and resting heart rate. Endurance athletes frequently have systolic pressures in the low 100s or even the 90s, paired with resting heart rates in the 40s and 50s. Their hearts pump more blood per beat, so they can maintain circulation at lower pressures and slower rates. A reading of 108/68 in someone who exercises regularly is about as unremarkable as it gets.
The vagus nerve plays a central role in this adaptation. It acts as a brake on heart rate and helps regulate cardiovascular function at rest. Regular exercise increases vagal tone, meaning the nerve’s resting influence on the heart grows stronger, slowing the pulse and contributing to lower blood pressure.21PubMed Central. Vagus Nerve Stimulation and the Cardiovascular System This is a sign of cardiovascular fitness, not a problem to solve. If you exercise frequently and your resting blood pressure sits at 108/68 or lower, it means your heart is working efficiently. The only time to look deeper is if you develop symptoms like fainting during exercise, which could indicate a structural or electrical issue rather than a simple fitness adaptation.