Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Sleep and metabolism are closely interconnected, and emerging evidence suggests that dietary composition may influence both sleep quality and key physiological functions such as glucose regulation, cardiovascular activity, and hormonal signaling. This study aims to investigate how a Western-style unhealthy diet versus a healthier, fiber-rich diet affects objective and subjective sleep measures, 24-hour physiological parameters, and a range of biomarkers related to cardiometabolic, neurodegenerative, and gut microbial function.
Metabolism is tightly regulated by sleep and interacts bidirectionally with diet. While it is well established that insufficient or disrupted sleep can impair glucose regulation, cardiovascular function, and promote unhealthy eating behaviors that promote cardiometabolic disease, less is known about how different dietary patterns impact subjective and objective sleep parameters, as well as related physiological systems.
The study will systematically investigate how consumption of an unhealthier "Western" diet, compared to a healthier diet, affects both objective and subjective sleep parameters, as well as 24-hour heart rate and blood pressure profiles, glucose variability, and hormonal and molecular biomarkers.
The study will be conducted as a 2-condition, randomized crossover study, with assessments in the field for about a week, followed by a multi-day stay for measurements under standardized laboratory conditions. Participants will be monitored using polysomnography, and wearable devices, including for continuous glucose and heart rate parameters, with multi-compartment sampling to assess diet-mediated responses across cardiometabolic, neurodegenerative, and microbial pathways. In field and in the lab, biological samples will be collected repeatedly across the day to establish diurnal rhythms.
Cognitive performance, mood, and subjective appetite will also be evaluated. By identifying diet-driven changes in sleep and related physiological functions, this study aims to provide mechanistic insights into how nutrition impacts sleep, cardiometabolic health parameters and molecular pathways.
Not provided
Not provided
Not provided
Not provided
Not provided
| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Healthy diet | Experimental | 'Low-fat dietary intervention' to be administered to participants |
|
| Unhealthier diet | Experimental | 'High-fat dietary intervention' to be administered to participants |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Low-fat dietary intervention | Other | Low-fat diet for approximately 1 week, preceding in-lab study period (approximately 2 days) under standardized conditions (total dietary exposure up to 9-10 days). |
| Measure | Description | Time Frame |
|---|---|---|
| Sleep Architecture and Neurophysiological Features | Objective registration and analysis of sleep, based on polysomnography or validated wearable devices to capture macrosleep, spectral and microsleep features. | Up to 9 nights on each diet |
| Change in 24-Hour Heart Rate Variability (HRV) | Continuous measurement of HRV, using a wearable device, focused on the metric Root Mean Square of the Successive Differences (RMSD); additional metrics (Standard Deviation of NN intervals (SDNN), low frequency to high frequency (LF/HF) ratio) analyzed for exploratory purposes. | Up to 9 days on each diet |
| Measure | Description | Time Frame |
|---|---|---|
| 24-Hour Heart Rate (HR) | Continuous measurement of heart rate using a wearable device | Up to 9 days on each diet |
| Heart Rate Response to Standardized Stair Stepping | ECG-based heart rate measured at baseline, during stepping and repeatedly (up to 5 min) post-stair stepping, to assess recovery, also analyzed in relation to sleep metrics. |
Not provided
Inclusion Criteria:
Exclusion Criteria:
Not provided
Not provided
Not provided
Not provided
| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Jonathan Cedernaes, MD, PhD | Contact | 0184710000 | jonathan.cedernaes@medsci.uu.se |
| Name | Affiliation | Role |
|---|---|---|
| Jonathan Cedernaes, MD, PhD | Uppsala University, Sweden | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Uppsala biomedical center | Recruiting | Uppsala | 75324 | Sweden |
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Participants will be studied in a crossover design both after a "healthy diet", and after an "unhealthy diet"
Not provided
Not provided
In the crossover condition, participants will not be briefed about what diet they will receive before the actual onset of any of the two dietary interventions
Not provided
| High-fat dietary intervention | Other | High-fat diet for approximately 1 week, preceding in-lab study period (approximately 2 days) under standardized conditions (total dietary exposure up to 9-10 days). |
|
| Baseline and day 7-9 of each diet period |
| Morning-to-Evening and 24-h blood pressure (BP) | Morning, evening, and 24-h ambulatory measurement of systolic blood pressure, also analyzed in relation to sleep metrics. | Up to 9 days on each diet |
| 24 Hour Continuous Glucose Levels | Continuous (24-h) monitoring of interstitial glucose for analysis of mean levels and variability metrics (e.g., SD, coefficient of variation, postprandial changes), also analyzed in relation to sleep metrics. | Up to 9 days on each diet |
| Levels of Blood-based Biomarkers | Changes in levels of molecular factors such as DNA, hormones/proteins and metabolites, due to the preceding dietary intervention, and also in relation to sleep metrics. | Up to 9 days on each diet |
| Levels of CNS biomarkers | Levels of CNS health biomarkers (such as brain-derived neurotrophic factor (BDNF), Tau (e.g. BD-tau) and Amyloid beta (Aβ) species, glial fibrillary acidic protein (GFAP), and Neurofilament light chain (NfL)). | Up to 9 days on each diet |
| Urinary Metabolite Levels | Urine levels of excretion molecules (such as melatonin breakdown metabolites). | Up to 9 days on each diet |
| Change in Metabolic Fuel Utilization | Change in metabolic fuel utilization as measured by respirometry, in response to the dietary interventions. | Up to 9 days on each diet |
| Levels of Fecal Metabolites | Changes in levels of fecal metabolites (such as short chain fatty acids, bile acids) due to each dietary intervention | Up to 9 days on each diet |
| Levels of Fecal Microbiota | Changes in fecal microbiota (metagenomic, compositional) due to each dietary intervention | Up to 9 days on each diet |
| Levels of Salival Biomarkers | Changes in levels of salival molecules (such as cortisol and melatonin), also in relation to sleep-circadian metrics. | Up to 9 days on each diet |
| Levels of Salival Microbiota | Changes in salival microbiota (metagenomic, compositional) due to each dietary intervention | Up to 9 days on each diet |
| Changes in glucose tolerance | Glucometabolic response to a standardized 2-h glucose tolerance test, also analyzed in relation to sleep-circadian metrics. | Day 8-9 on each diet |
| Levels of Immune Cells | Immune cell profile across the day in response to each diet | Up to 9 days on each diet |
| Change in Subjective Sleep Quality | Change in self-reported sleep quality as assessed by the Pittsburgh Sleep Quality Index (PSQI), supplementing objective sleep data. Total Score (0-21; higher = worse). | Up to 9 days on each diet |
| Subjective Hunger and Appetite Levels | Self-reported hunger and appetite across the day, and prior to and after meals, as assessed via visual analogue scales (VAS, i.e., with scores 0 for the lowest subjective rating, to 100 for the highest rating) | Up to 9 days on each diet |
| Body Temperature | Body temperature measured via wearable sensors to assess effects of dietary interventions on thermoregulation and its relationship to sleep, circadian rhythms and metabolism. | Up to 9 days on each diet |
| Change in Composite Cognitive Performance Score | Composite score from four tasks:
All scores will be standardized and averaged; higher composite values indicate better cognitive performance. | Up to 9 days on each diet |
| Changes in mental wellbeing | Self-reported assessment of mental wellbeing using validated subjective scales (visual analogue scales going from lowest 0 to highest of 100), to evaluate effects of diet and sleep. | Up to 9 days on each diet |
| Changes in Central Hemodynamics | Morning, evening, and 24-h ambulatory levels of central hemodynamics reflecting central blood pressure and arterial resistance, also analyzed in relation to sleep metrics | Up to 9 days on each diet |
| Effect Modification by Biological Sex | Exploratory subgroup analysis to determine if male vs. female participants differ in response to dietary interventions, for primary and secondary outcomes | Based on data collected up to 9 days on each diet |
| Effect Modification by Cardiorespiratory Fitness | Exploratory analysis to determine whether cardiorespiratory fitness parameters modulates responses to how the diets impact primary and secondary outcomes. | Based on data collected up to 9 days on each diet |
| Change in Dim Light Melatonin Onset | Dim Light Melatonin Onset as assessed via repeatedly measured melatonin levels, measured in the evening under standardized conditions | Up to 9 days on each diet |
| Levels of molecular biomarkers in dried blood spots | Analysis of levels of molecular biomarkers (such as CRP) in dried blood spots from finger samples, and how these correlate with biomarker levels from peripheral venous blood samples | Up to 9 days on each diet |