An interventional study of Circadian Rhythm Optimization in Aging, Healthy, Blood Sugar; High and Blood Sugar (Glucose) Control, sponsored by Salk Institute for Biological Studies. Active, not recruiting at 1 site in United States. Open to participants aged 50 Years to 80 Years. Per ClinicalTrials.gov, last updated 2025-12-31.
Sponsored by Salk Institute for Biological Studies · Not applicable, Interventional, and Treatment
In this single arm intervention trial, the investigators will assess the impact of a personalized lifestyle plan, centered on supporting biological rhythms, on blood sugar levels, physical, cognitive and immune function in older adults with a habitual eating window of 12 hours or more, and elevated blood glucose levels.
All participants will be provided with a personalized circadian rhythm optimization plan (CRO) centered on improving (1) diet, (2) exercise (3) sleep habits based on their body's natural rhythms. The study includes a 2-week screening/baseline assessments, with follow-up health assessments at 2-months.
The purpose of this study is to assess if modifying lifestyle behaviors such as improving nutrition quality while consolidating caloric intake to a consistent 8-10 hour window, incorporating regular exercise and ensuring a consistent sleep window will help improve glucose (sugar) regulation, physical, cognitive and immune function and improve other markers of metabolic, cardiovascular health and aging (i.e. lipid levels, inflammation markers, etc.).
Circadian clocks ("circa" means approximately and "dia" means day) are daily rhythms in physiology and behavior (activity, sleep, eating pattern) that help the body anticipate and adapt to predictable events in the environment. These rhythms are generated and maintained by biological clocks that are present in the brain and almost every organ. Remarkably, even in the absence of any timing information from a device, the human body can keep track of time and thereby help us eat and sleep at optimum times. However, our lifestyle and work schedules can lead us to eat, exercise, and sleep at times that the clocks in our body are not prepared for. When these abnormal daily patterns continue for several weeks or years, it can affect our health in many ways including increased body weight, poor sleep, and elevated risk for various chronic diseases.
A growing body of preclinical research has shown that synchronizing behaviors, such as food intake, exercise, and light exposure, with the body's biological clock improves skeletal muscle function, cognitive performance, and inflammatory markers. Clinical studies have further validated these findings, showing that circadian-based interventions, such as time-restricted eating (TRE), which restricts all caloric intake to a personalized consistent daily eating window, daytime light exposure and exercise have been shown to improve mood, sleep quality and cardiometabolic health. Despite these promising individual findings, no study has comprehensively examined the combined effects of TRE, structured exercise and optimized sleep schedule as an integrated strategy to restore circadian alignment and reverse key physiological markers of aging in older adults.
In this study, the investigators are interested in evaluating the effects of modifying eating, activity and sleeping patterns on age related health outcomes in older adults with elevated blood sugar levels. All participants will be provided with a personalized circadian rhythm optimization (CRO) program centered on (1) consuming a Mediterranean diet within a personalized 8-10-hour daytime window, (2) increasing daytime light exposure and reducing bright light at night, (3) incorporating 150 minutes of moderate-intensity aerobic exercise each week (4) holding a consistent 7-9 hour sleep schedule (5) taking supplements based on individual needs.
The study is 90-days including a 2-week screening/baseline assessment followed by a 2-week period to developed their personalized plan based off their baseline assessments and finally a 8-week guided intervention period. Health assessments will be taken at screening/baseline, and at 90 days. Assessments will include cognitive function (cognitive assessment battery), physical function (VO2 Max, isometric strength, short physical performance battery), dietary recall (ASA24), blood tests (biomarkers of cardiometabolic health and immune parameters), glycemic regulation (Continuous Glucose Monitors), body composition ( bioelectrical impedance scan), dietary intake (logged on the myCircadianClock smartphone app), sleep and quality of life questionnaires, and activity, sleep, and wrist temperature (actigraphy watch) and subclavian and ankle surface temperature (non-invasive temperature sensor).
699 studies on the registry are indexed under Hyperglycemia; 105 are open to participants now.
This study's planned enrollment of 16 is below the median of 46 across 521 interventional studies indexed under Hyperglycemia.
Browse Hyperglycemia studies →Salk Institute for Biological Studies is the lead sponsor of 2 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Each participant will be provided with a personalized plan centered on synchronizing their behavior with their endogenous rhythm.
Behavioral: Circadian Rhythm Optimization
Participants will follow a Mediterranean diet while consuming all calories within a personalized 8-10 hour daytime window. They will increase daytime light exposure to at least one hour per day, engage in a minimum of 150 minutes of moderate-intensity aerobic exercise each week (including at least two sessions lasting no less than 60 minutes), maintain a consistent 7-9 hour sleep schedule, and take supplements as recommended based on individual needs. Participants will also record all food and beverage intake, as well as exercise, using the myCircadianClock app.
HbA1c (%)
HbA1c levels (%) as assessed by fasting blood draw
Time frame: Baseline and 90 days
Grip Strength
Maximal grip force (Kg)
Time frame: Baseline and 90 days
Isometric Knee Strength
Maximal force output for knee flexion and extension (Kg)
Time frame: Baseline and 90 days
VO2 Max
Maximal oxygen consumption (mL/kg/min).
Time frame: Baseline and 90 days
Time to 85% of Age Predicted Maximal Heart Rate
Time to 85% of age predicted maximal heart rate (mins).
Time frame: Baseline and 90 days
Flanker Inhibitory and Control and Attention Test (Fully-Corrected T-score)
Flanker Inhibitory and Control and Attention Test (Fully-Corrected T-score) assessed through NIH cognitive assessment battery. The score compares an individual's cognitive performance to a nationally representative norming sample correcting for age, sex, race/ethnicity, and educational attainment.
Time frame: Baseline and 90 days
Dimensional Change Card Sort (Fully-Corrected T-score)
Dimensional Change Card Sort (Fully-Corrected T-score) assessed through NIH cognitive assessment battery. The score compares an individual's cognitive performance to a nationally representative norming sample correcting for age, sex, race/ethnicity, and educational attainment.
Time frame: Baseline and 90 days
Pattern Comparison Processing Speed Test (Fully-Corrected T-score)
Pattern Comparison Processing Speed Test (Fully-Corrected T-score) assessed through NIH cognitive assessment battery. The score compares an individual's cognitive performance to a nationally representative norming sample correcting for age, sex, race/ethnicity, and educational attainment.
Time frame: Baseline and 90 days
Picture Sequence Memory test (Fully-Corrected T-score)
Picture Sequence Memory test (Fully-Corrected T-score) assessed through NIH cognitive assessment battery. The score compares an individual's cognitive performance to a nationally representative norming sample correcting for age, sex, race/ethnicity, and educational attainment.
Time frame: Baseline and 90 days
Trail Making Test
Trail making test part A and B will be assessed by the time to completion (seconds) for each assessment.
Time frame: Baseline and 90 days
Glucagon (pg/mL)
Glucagon (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
Leptin (ng/mL)
Leptin (ng/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-1α (pg/mL)
IL-1α (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-1β (pg/mL)
IL-1β (pg/mL)assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-2 (pg/mL)
IL-2 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-3 (pg/mL)
IL-3 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-4 (pg/mL)
IL-4 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-5 (pg/mL)
IL-5 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-6 (pg/mL)
IL-6 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-7 (pg/mL)
IL-7 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-8
IL-8 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-9 (pg/mL)
IL-9 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-10 (pg/mL)
IL-10 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-12p70 (pg/mL)
IL-12p70 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-13 (pg/mL)
IL-13 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-15 (pg/mL)
IL-15 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-16 (pg/mL)
IL-16 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-17A (pg/mL)
IL-17A (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-17F (pg/mL)
IL-17F (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-18 (pg/mL)
IL-18 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90-days
IL-20 (pg/mL)
IL-20 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-21 (pg/mL)
IL-21 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-22 (pg/mL)
IL-22 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-23 (pg/mL)
IL-23 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-27 (pg/mL)
IL-27 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-28 (pg/mL)
IL-28 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-33 (pg/mL)
IL-33 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
MCP-1 (pg/mL)
MCP-1 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
MCP-2
MCP-2 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
MCP-3 (pg/mL)
MCP-3 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
MCP-4 (pg/mL)
MCP-4 (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
TGFα (pg/mL)
TGFα (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
TNFβ (pg/mL)
TNFβ (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
EGF (pg/mL)
EGF (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
TNF-α (pg/mL)
TNF-α (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
Ghrelin (pg/mL)
Ghrelin (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90-days
IGF-1 (ng/mL)
IGF-1 (ng/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IGF-2 (ng/mL)
IGF-2 (ng/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IL-1RA (pg/mL)
IL-1RA (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
TRAIL (pg/mL)
TRAIL (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
VEGF-A (pg/mL)
VEGF-A (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
IGFBP-1 (ug/mL)
IGFBP-1 (ug/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
GIP (pg/mL)
GIP(pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90-days
GLP-1 (pmol/L)
GLP-1 (pmol/L) assessed through fasting blood draw.
Time frame: Baseline and 90 days
Total Recall (T-score)
Total Recall (T-score) as assessed through Hopkins Verbal Learning Test - Revised. T-score is adjusted for participant's age.
Time frame: Baseline and 90-days
Delayed Recall (T-score)
Delayed Recall (T-score) as assessed through Hopkins Verbal Learning Test. T-score is adjusted for participant's age.
Time frame: Baseline and 90-days
Retention Percentage (T-score)
Retention Percentage (T-score) as assessed through Hopkins Verbal Learning Test - Revised. T-score is adjusted for participant's age.
Time frame: Baseline and 90-days
Recognition Discrimination Index (T-score)
Recognition discrimination index as assessed through Hopkins Verbal Learning Test-Revised. T-score is adjusted for participant's age.
Time frame: Baseline and 90-days
Cognition Fluid Composite (Fully-Corrected T-score)
Cognition Fluid Composite (Fully-Corrected T-score) as assessed through a composite score of several tests, namely the Flanker inhibitory control and attention test, the dimensional change card sort test, the picture sequence memory test, the list sorting working memory test, and the pattern comparison processing speed test. The score compares an individual's cognitive performance to a nationally representative norming sample correcting for age, sex, race/ethnicity, and educational attainment.
Time frame: Baseline and 90-days
Total Body Fat Mass (kg)
Total Body Fat Mass (kg) assessed by bioelectrical impedance scan
Time frame: Baseline and 90 days
Fat Free Mass
Whole body fat free mass (kg) assessed by bioelectrical impedance scan
Time frame: Baseline and 90 days
Intra-Daily Glycemic Variability: CONGA (A.U.)
Continuous Overall Net Glycemic Action (CONGA) assessed via continuous glucose monitor
Time frame: Baseline and 90-days
Inter-Daily Glycemic Variability: MODD (mg/dL)
Mean of Daily Differences (MODD) assessed via continuous glucose monitor
Time frame: Baseline and 90 days
Glycemic Variability: MAGE (mg/dL)
Mean Amplitude of Glycemic Excursions (MAGE) assessed by continuous glucose monitor
Time frame: Baseline and 90 days
Mean Glucose (mg/dL)
Mean Glucose assessed by continuous glucose monitor
Time frame: Baseline and 90 days
Fasting Glucose
Fasting Glucose (mg/dL) assessed through fasting blood draw
Time frame: Baseline and 90 days
Fasting Insulin
Fasting insulin (μU/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
HOMA-IR
HOMA-IR assessed through fasting blood draw
Time frame: Baseline and 90 days
Skin Surface Temperature
Mean daily Skin surface temperature at the wrist, ankle and subclavian region of the chest (Degrees C) assessed through actigraphy watch and non-invasive skin temperature probe.
Time frame: Baseline and 90 days
Short Physical Performance Battery
A sum of the scores from the Chair Stand Test , Gait Speed Test, Side-By-Side- Stand, Semi-Tandem Stand \& Tandem Stand Balance Tests. The scoring for each assessment will be based off the previously established and widely used Short Physical Performance Battery Protocol and score sheet where the Chair Stand Test , Gait Speed Test and balance tests scoring are based off the participants ability to rise from the chair, duration is takes to cover 4m distance (seconds) and duration they are able to balance (seconds) respectively.
Time frame: Baseline and 90 days
Quality of Life Assessment
Short-Form 36 (SF-36) Survey. Scores range from 0-100 (an average of all questions which each have a 0-100 scale), with 100 indicating better physical and emotional health.
Time frame: Baseline and 90 days
Triglycerides (mg/dL)
Triglycerides (mg/dL) from fasted blood draw.
Time frame: Baseline and 90 days
Total Cholesterol (mg/dL)
Total cholesterol (mg/dL) from fasted blood draw.
Time frame: Baseline and 90 days
HDL-cholesterol (mg/dL)
HDL-cholesterol (mg/dL) from fasted blood draw.
Time frame: Baseline and 90 days
hs-CRP (mg/dL)
hs-CRP (mg/dL) from a fasted blood draw.
Time frame: Baseline and 90 days
LDL Particle number (nmol/L)
LDL Particle number (nmol/L) assessed by NMR lipoprotein profiles from a fasted blood draw.
Time frame: Baseline and 90 days
Apo A (mg/dL)
Apo A (mg/dL) assessed by NMR lipoprotein profiles from a fasted blood draw.
Time frame: Baseline and 90 days
Apo B (mg/dL)
Apo B (mg/dL) assessed by NMR lipoprotein profiles from a fasted blood draw.
Time frame: Baseline and 90 days
Apo A/B ratio
Apo A/B ratio assessed by NMR lipoprotein profiles from a fasted blood draw.
Time frame: Baseline and 90 days
Very Low Density Lipoprotein (VLDL) Size (nm)
VLDL size (nm) assessed by NMR lipoprotein profiles from a fasted blood draw.
Time frame: Baseline and 90 days
HDL Particle number (umol/L)
HDL Particle number (umol/L) assessed by NMR lipoprotein profiles from a fasted blood draw.
Time frame: Baseline and 90 days
Thyroid-Stimulating Hormone (µU/mL)
Thyroid-Stimulating Hormone (µU/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
Sex Hormone Binding Globulin (nmol/L)
Sex Hormone Binding Globulin (nmol/L) assessed through fasting blood draw
Time frame: Baseline and 90 days
Gamma-Glutamyl Transferase (IU/L)
Gamma-Glutamyl Transferase (IU/L) assessed through fasting blood draw
Time frame: Baseline and 90 days
Cystatin C (mg/L)
Cystatin C (mg/L) assessed through fasting blood draw
Time frame: Baseline and 90 days
N-terminal pro-B-type natriuretic peptide (pg/mL)
N-terminal pro-B-type natriuretic peptide (pg/mL) assessed through fasting blood draw
Time frame: Baseline and 90 days
Vitamin D
Vitamin D levels (ng/mL) assessed through fasting blood draw.
Time frame: Baseline and 90-days
Plan to share: Yes — Investigators will report deidentified individual participant data for outcomes that are reported in scientific publications (text, tables, figures, and appendices).
Supporting information: Study protocol, Sap
No publications or documents are linked to this record.
This study is active, not recruiting, as verified in Dec 2025. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Salk Institute for Biological Studies