Browse the evidence

Sleep duration of approximately 7 hours per day is associated with the lowest risk of all-cause mortality and cardiovascular events, while both shorter and longer durations increase risk in a U-shaped dose-response relationship.

Aim for approximately 7 hours of sleep per night to minimize your risk of heart disease and early death. Both sleeping significantly less than 7 hours and significantly more than 7 hours is linked to higher health risks. This applies to generally healthy adults; if you have underlying conditions, consult your doctor.

Experiencing weight stigma prospectively causes weight gain and increased risk of obesity, independent of baseline BMI, through obesogenic behavioral and physiological pathways.

Stop using shame as a tool for weight management. The evidence shows that feeling stigmatized actually increases the risk of weight gain and poor metabolic health through stress and behavioral avoidance. Focus on health behaviors (sleep, activity, nutrition) without focusing on weight or size, and avoid stigmatizing language in yourself and others.

There is moderate evidence that sedentary behavior is associated with the incidence of endometrial, colon, and lung cancer, but insufficient evidence to determine if bout length or breaks in sedentary behavior are associated with health outcomes.

Sedentary behavior is linked to higher rates of colon, lung, and endometrial cancer. While we don't yet know if 'breaking up' sitting time helps, reducing your total sitting time is a prudent step for cancer prevention.

Wrist-worn optical sensors provide accurate heart rate measurements (median error <5%) during controlled laboratory cycling and running, but fail to accurately estimate energy expenditure (median error >20%) across all activities.

Use your wrist-worn device to track heart rate zones for training intensity; it is generally accurate for this purpose. Do not rely on the calorie/energy expenditure numbers for weight loss decisions, as they are frequently off by 20% or more. Focus on effort and duration rather than the specific caloric burn reported.

Device error in heart rate measurement is significantly higher in males, individuals with darker skin tones, and those with higher BMI compared to females, lighter-skinned individuals, and lower BMI individuals.

If you have darker skin or a higher BMI, be aware that your wrist-worn heart rate monitor may be less accurate. Use the data as a general trend rather than an exact number, and verify with manual pulse checks if necessary.

Socioeconomic disparities exist in dietary improvements, with higher-income and higher-education individuals showing greater improvements in macronutrient composition and diet quality.

If you have limited resources, focus on the most impactful swaps: reducing added sugars and increasing whole grains. These changes are achievable and contribute to overall diet quality, even if progress is slower than for higher-income groups.

Self-report sleep quality questionnaires (specifically PSQI, AIS, ISI, MSQ, JSS, LSEQ, SLEEP-50, ESS) demonstrate good internal reliability and construct validity, making them suitable for clinical and epidemiological screening despite objective measures like polysomnography being impractical.

Use validated self-report questionnaires like the PSQI or ISI to assess sleep quality. They are cost-effective, easy to administer, and provide reliable data for screening poor sleepers in both clinical and research settings, especially when objective measures like PSG are not feasible.

A heuristic algorithm (HDCZA) applied to raw wrist-worn accelerometer data can accurately estimate the Sleep Period Time window (SPT-window) without requiring a sleep diary.

To track your sleep without keeping a diary, use a wrist-worn fitness tracker that records raw acceleration data. Ensure it is worn on your non-dominant wrist continuously. The device's software (using algorithms like HDCZA) will automatically determine your sleep window based on movement and body angle, providing a reliable estimate of your sleep duration and timing without you needing to manually log your bedtime or wake time.

Consumer food choices are determined by intention, which is driven by attitude, subjective norm, and perceived behavioral control, rather than by rational calculation of product attributes alone.

To change food habits, focus on shaping social norms and reducing perceived barriers (control) rather than just providing nutritional information. If people feel social pressure to eat junk food or feel they lack the time/skill to cook healthy meals, intention will remain low regardless of knowledge.

Walking as a mode of active commuting is associated with lower risk of cardiovascular disease (CVD) incidence and mortality, but not all-cause mortality or cancer outcomes, compared to non-active commuting.

Walking to work is a great way to protect your heart. This study links walking to lower heart disease risk. However, it didn't significantly lower death rates or cancer risk like cycling did. If you can't cycle, walking is still a valuable health habit, especially if you walk longer distances.

Mixed-mode commuting that includes cycling is associated with lower risks of all-cause mortality, cancer incidence, and cancer mortality compared to non-active commuting.

If you can't cycle the whole way, try mixing it in. This study links mixed-mode commuting (driving + cycling part of the way) to lower death and cancer risks. It didn't help as much as pure cycling, but it's still better than driving alone. Walking as part of a mixed commute didn't show benefits.

Self-reported sleep duration exceeding 8 hours per night is associated with a moderate increase in all-cause mortality, with risk ratios rising significantly for 9, 10, and 11 hours of sleep.

Aim for 7 to 8 hours of sleep. While sleeping less than 7 hours showed no significant increased mortality risk in this specific meta-analysis, sleeping more than 8 hours was associated with a moderate but significant increase in all-cause mortality. If you consistently require more than 8 hours of sleep, consider it a marker for elevated cardiovascular risk and consult a healthcare provider to rule out underlying conditions.

Subjective poor sleep quality is associated with a significant increase in coronary heart disease (CHD) risk, but not with all-cause mortality or other cardiovascular outcomes.

Focus on sleep quality, not just duration. If you frequently report poor sleep quality (restless, disturbed nights), you have a 44% higher risk of coronary heart disease. Address sleep disturbances through sleep hygiene or medical evaluation, as this is a specific risk factor for heart disease.

Extreme sleep durations (≤4 hours or ≥10 hours per night) are associated with significantly faster rates of global cognitive decline in older adults compared to a reference duration of 7 hours per night.

If you are over 45, aim for approximately 7 hours of sleep per night. Both sleeping 4 hours or less and 10 hours or more are associated with faster cognitive decline. If you consistently sleep outside this range, consider monitoring your cognitive health and consulting a healthcare provider to rule out underlying issues like sleep apnea (for long sleepers) or insomnia (for short sleepers).

Fiscal disincentives (taxes on unhealthy foods) paired with incentives (subsidies for healthy foods) are more effective at improving population diet quality and reducing health disparities than voluntary education or labeling alone.

If you are a policymaker, prioritize taxes on sugary drinks and junk food, but use the revenue to subsidize fruits and vegetables. This approach has stronger evidence for improving health than just telling people to eat better.

Government procurement standards for schools, worksites, and healthcare settings are low-cost, sustainable, and effective interventions for improving diet quality.

If you manage a cafeteria or food service, implement strict nutrition standards for all food purchased. This is a proven, low-cost way to improve the health of the people you serve without relying on their willpower.

Motivational Interviewing (MI) and avoiding stigmatization are critical components of obesity management that improve patient adherence, self-esteem, and treatment efficacy.

Work with your doctor to build a trusting relationship. Use Motivational Interviewing techniques to identify your own reasons for wanting to change. Focus on small, realistic goals and celebrate progress in health, not just weight.

The observed antidepressant effect of resistance exercise training is smaller in trials where allocation and/or assessment was blinded, indicating that unblinded trials may overestimate the effect due to bias.

Be aware that the large effects often cited in unblinded studies may be inflated by participant expectations. However, even in rigorous, blinded trials, resistance exercise training still produces a significant, moderate reduction in depressive symptoms.

Adopting an extended unhealthy lifestyle profile (including smoking, alcohol, poor diet, low physical activity, high TV viewing, and sleep duration) significantly increases all-cause and cardiovascular disease mortality risk, with the magnitude of this risk disproportionately higher in socioeconomically deprived populations.

Your lifestyle choices (diet, activity, sleep, substance use) have a massive impact on your longevity, and this impact is even more severe if you live in a deprived area. To maximize your health, you must address all these factors, not just one. However, recognizing that systemic factors play a role, seeking support and focusing on what you can control within your environment is critical.

Implementation of a sugar-sweetened beverage (SSB) excise tax leads to a significant decline in the volume of SSB sales, accompanied by a substitution effect toward untaxed beverages (particularly water), without increasing overall consumer spending per transaction.

A tax on sugary drinks successfully reduces the amount of sugary drinks sold by making them relatively more expensive. Consumers respond by buying less sugary drinks and more water or other untaxed beverages, keeping their total grocery bill roughly the same. This policy lever works through economic substitution rather than direct health mandates.

Primary care behavioral counseling interventions targeting diet and physical activity produce small, statistically significant improvements in intermediate cardiovascular risk factors (blood pressure, cholesterol, BMI) in adults without known CVD risk factors, but do not consistently improve long-term health outcomes like mortality or morbidity.

If you are generally healthy, talking to your doctor about diet and exercise will likely lower your blood pressure and cholesterol slightly. However, do not expect this counseling alone to prevent heart attacks or death. The benefits are modest and require sustained effort (high-intensity counseling yields better results).

Urban residence, higher socioeconomic status, and female sex are significantly associated with increased prevalence of overweight, obesity, hypertension, and diabetes in sub-Saharan African populations, contradicting the traditional view that these conditions are primarily diseases of affluence in high-income countries.

If you live in an urbanizing area, your risk for obesity, high blood pressure, and diabetes is significantly higher than if you lived in a rural subsistence farming environment, regardless of your income level. Focus on maintaining physical activity and monitoring blood pressure and blood sugar, as these conditions are emerging rapidly in these populations.

Urban women face the highest risk of multimorbidity (having two or more of hypertension, diabetes, or obesity) compared to rural women and men in either setting.

Urban women should be particularly vigilant about managing multiple health markers simultaneously. Because the risk of having high blood pressure, high blood sugar, and excess weight together is highest for this group, regular screening for all three is essential.

A significant proportion of individuals with diagnosed hypertension or diabetes in this population have poorly controlled conditions, with less than half of those on medication achieving target blood glucose or blood pressure levels.

Being on medication for high blood pressure or diabetes does not guarantee your numbers are under control. If you are on medication, you need regular monitoring to ensure it is working, as a significant number of people do not reach target levels.