Sleep disorders affect a large population, with demand for sleep support on the rise. Although previous research has explored the relationship between specific nutrients and insomnia, comprehensive analyses of daily eating patterns of macro- and micronutrients remain limited.
Diets high in sodium, low in potassium, or both, have been associated with altered nocturnal blood pressure decrease (when blood pressure does not decline as much as it normally does at night).
At the same time, nocturnal hypertension has been linked to sleep disturbances.
As such, a cross-sectional study in Japan examined the relationship between potassium and sodium intake and insomnia among healthy Japanese adults.
Dietary data on energy intake and consumption of protein, fat, carbohydrates, sodium, and potassium during breakfast, lunch, dinner, and snacks spanning January to February 2021 were derived from Asken, a widely used Japanese food-logging mobile app.
Users can input ingredients, dishes, and portion sizes into the app, which automatically calculates calorie and nutritional intake by referencing the Standard Tables of Food Composition in Japan, 2020 (Eighth Revised Edition), as determined by the country’s Ministry of Education, Culture, Sports, Science and Technology.
The app boasts over 11.2m downloads as of November 2024. Self-reported food records accumulated on the app have been validated as reliable for research purposes.
As part of the study, online survey responses were obtained from 4,568 app users (3,320 women and 1,248 men) aged between 20 and 64 at the end of January 2021.
Sleep disturbances were assessed using the Athens Insomnia Scale (AIS), a self-administered psychometric questionnaire designed to evaluate sleep disorders, particularly insomnia.
The questionnaire consists of eight items, with total scores classified into three groups according to symptom severity — normal (scores of 3 or less), subclinical insomnia (scores of greater than 3 but less than 6), and clinical insomnia (scores of 6 or more).
The results showed that total daily potassium intake was inversely associated with log AIS score (p = 0.034).
When consumption during each meal (breakfast, lunch, dinner, and snacks) was analysed, only potassium intake at dinner remained significantly associated with AIS score (p = 0.003).
“Our findings suggest that potassium intake may be related to sleep quality. Higher potassium intake, especially at dinner, indicates fewer sleep disturbances [based on AIS scores]. This study provides a foundation for future intervention studies and personalised dietary recommendations,” the authors wrote.
Potassium power
Previous studies have shown that lower potassium intake is associated with short sleepers, sleepiness during the day, poor sleep quality and sleep efficiency, and nighttime awakening.
There are several potential mechanisms explaining the relationship between potassium intake and sleep.
Firstly, adequate potassium levels are critical for proper muscle contraction and relaxation, as the mineral plays a key role in transmitting electrical signals in nerve fibres and muscle cells, thereby regulating overall muscle function and contributing to sleep patterns.
Additionally, potassium is essential for neurotransmitter function, which is crucially involved in regulating sleep and wakefulness.
Studies have also demonstrated that potassium reduces both systolic and diastolic blood pressure. Given the well-documented association between poor sleep and hypertension, these findings suggest that potassium intake could lead to better sleep by regulating blood pressure.
However, the mechanism underlying why dinner intake is particularly significant remains to be investigated.
“To better understand the observed association between potassium intake and insomnia, future research should include both dietary records and blood pressure data. Longitudinal and intervention studies will also be needed to establish causal relationships and explore other factors influencing sleep.”
Link between sodium intake and sleep to be verified
Several studies have found sodium or salt intake to be associated with sleep maintenance difficulties, later sleep times, and a higher probability of insomnia.
For example, a Japanese cross-sectional study showed that energy-adjusted sodium intake was positively correlated with sleep duration among healthy Japanese adult men.
In the present study, however, no significant association between sodium intake and AIS scores was discovered. This calls for further evidence to verify the relationship between sodium intake and sleep.
The Japanese diet is characterised by high sodium and low potassium intake, or a high sodium-to-potassium ratio.
The sodium-to-potassium ratio is recognised as a superior indicator for assessing blood pressure outcomes and hypertension incidence, compared to individual measures of sodium or potassium.
The sodium-chloride cotransporter (NCC), expressed in the kidneys, is a key molecule in the regulation of urinary potassium excretion. Consuming a low-potassium diet activates the NCC, promoting sodium reabsorption.
Conversely, a high-potassium diet strongly suppresses NCC activation, resulting in increased urinary sodium and potassium excretion.
Nevertheless, the results in this study did not find any meaningful association between the sodium-to-potassium intake ratio and AIS scores.
Source: Nutrients
https://doi.org/10.3390/nu17010148
“The Association of Sodium or Potassium Intake Timing with Athens Insomnia Scale Scores: A Cross-Sectional Study”
Authors: Taiki Okamoto, et al
