It turns out that an important tool for improving sleep quality may have been hiding in plain sight in the produce aisle. Researchers at the University of Chicago Medicine and Columbia University found that eating more fruits and vegetables during the day was associated with sleeping more soundly later that same night.

“Dietary modifications could be a new, natural and cost-effective approach to achieve better sleep,” said co-senior author Dr. Esra Tasali, who is the director of the UChicago Sleep Center. “The temporal associations and objectively-measured outcomes in this study represent crucial steps toward filling a gap in important public health knowledge.”

Studies have shown that inadequate sleep can cause people to gravitate towards unhealthier diets higher in fat and sugar. However, despite the far-reaching effects of sleep on public health and even economic productivity, doctors and scientists know far less about how diet can affect sleep patterns.

In previous observational studies, high fruit and vegetable intakes were associated with better self-reported overall sleep quality, but this new study was the first to draw a temporal connection between a given day’s dietary choices and objectively-measured sleep quality that same night.

Healthy young adults who participated in the study reported their food consumption each day with an app and wore a wrist monitor, allowing the researchers to objectively measure their sleep patterns. The study analyzed “sleep fragmentation,” which is an index that reflects how often someone awakens or shifts from deep to light sleep throughout the night.

The researchers found that each day’s diet was correlated with meaningful differences in the subsequent night’s sleep. Participants who ate more fruits and vegetables during the day tended to have deeper, more uninterrupted sleep that same night, as did those who consumed more healthy carbohydrates like whole grains.

Based on their findings and statistical modeling, the researchers estimate that people who eat the CDC-recommended five cups of fruits and veggies per day could experience a 16% improvement in sleep quality compared to people who consume no fruits or vegetables. “Sixteen percent is a highly significant difference,” said Dr. Tasali. “It’s remarkable that such a meaningful change could be observed within less than 24 hours.”

Future studies will help establish causation, broaden the findings across diverse populations, and examine the underlying mechanisms of digestion, neurology, and metabolism that could explain the positive impact of fruits and vegetables on sleep quality. However, based on current data, the experts confidently advise that regularly eating a diet rich in complex carbohydrates, fruits, and vegetables is best for long-term sleep health.

Health Benefits from Drinking Black Coffee

Tufts University researchers are now reporting an association between coffee consumption and mortality. However, the risks change with the amount of sweeteners and saturated fat added to the beverage. Published online in The Journal of Nutrition,  the study found that consumption of 1-2 cups of caffeinated coffee per day was linked to a lower risk of death from all causes and death from cardiovascular disease. 

Black coffee and coffee with low levels of added sugar and saturated fat were associated with a 14% lower risk of all-cause mortality as compared to no coffee consumption. The same link was not observed for coffee with high amounts of added sugar and saturated fat. 

“Coffee is among the most-consumed beverages in the world, and with nearly half of American adults reporting drinking at least one cup per day, it’s important for us to know what it might mean for health,” said senior study author Fang Fang Zhang, who is with Tufts University in Boston. “The health benefits of coffee might be attributable to its bioactive compounds, but our results suggest that the addition of sugar and saturated fat may reduce the mortality benefits.” 

The study analyzed data from nine consecutive cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. These surveys are linked to National Death Index Mortality Data. The study included a nationally representative sample of 46,000 adults aged 20 years and older who completed valid first-day 24-hour dietary recalls. 

Coffee consumption was categorized by type (caffeinated or decaffeinated), sugar, and saturated fat content. Mortality outcomes included all-cause, cancer, and cardiovascular disease. Low added sugar (from granulated sugar, honey, and syrup) was defined as under 5% of the Daily Value, which is 2.5 grams per 8-ounce cup or approximately half a teaspoon of sugar. Low saturated fat (from milk, cream, and half-and-half) was defined as 5% of the Daily Value, or 1 gram per 8-ounce cup or the equivalent of 5 tablespoons of 2% milk, 1 tablespoon of light cream, or 1 tablespoon of half-and-half.    

In the study, consumption of at least one cup per day was associated with a 16% lower risk of all-cause mortality. At 2-3 cups per day, the link rose to 17%. Consumption beyond three cups per day was not associated with additional reductions, and the link between coffee and a lower risk of death by cardiovascular disease weakened when coffee consumption was more than three cups per day. No significant associations were seen between coffee consumption and cancer mortality. 

“Few studies have examined how coffee additives could impact the link between coffee consumption and mortality risk, and our study is among the first to quantify how much sweetener and saturated fat are being added,” said study author Bingjie Zhou, Boston, Massachusetts. “Our results align with the Dietary Guidelines for Americans which recommend limiting added sugar and saturated fat.” 

John Schieszer is an award-winning national journalist and radio and podcast broadcaster of The Medical Minute.  He can be reached at medicalminutes@gmail.com