Sleep
Conditions
Keywords
sleep duration, blood pressure, vasodilation, cognitive function
Brief summary
Sleep duration has received much attention in recent years due to strong evidence that not enough sleep can increase risk for a number of diseases and disorders. Research is emerging that too much sleep also has a negative impact on health, particularly higher risk for myocardial infarction and stroke. The investigators hypothesize that long duration sleep has the ability to impair peripheral and cerebral vascular function in middle-aged to older adults.
Detailed description
The aim of this study is to compare the effect of long duration sleep (\>9 hours) to recommended levels of sleep (7-8 hours) in a crossover designed study requiring adults to maintain each prescribed sleep duration for one week. Ambulatory brachial and central aortic blood pressure will be measured during sleep, while cerebrovascular reactivity, carotid artery hemodynamics (e.g., flow pulsatility), aortic pulse wave reflections, cognitive function, and peripheral vasodilatory function will be measured before and after each sleep protocol. A secondary objective of this study is to understand whether aerobic exercise can improve vascular function under conditions of different sleep durations. This information will shed light upon the impact of sleep parameters on exercise-induced improvements in vascular function.
Interventions
BEHAVIORALSleep duration
Participants will be asked to alter time in bed to achieve specified sleep durations.
Sponsors
American Heart Association
Texas Tech University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
NONE
Intervention model description
This project will be a randomized crossover study. Each week will consist of a different time in bed schedule of either 8 or 11 hours time in bed (TIB). The investigators estimated that about 11 hours in bed will result in at least 9 hours of total sleep time (i.e., long duration sleep). Laboratory testing will occur after five consecutive nights of either 8h or 11h TIB to assess the effect of sleep duration on vascular function, and after the sixth consecutive night of TIB to assess the effect of exercise on vascular function under different sleep conditions.
Eligibility
Sex/Gender
ALL
Age
40 Years to 79 Years
Healthy volunteers
Yes
Inclusion criteria
* recreationally active * reporting no recent history of sleep problems * not taking sleep-inducing medication * not diabetic (fasting blood glucose \<126 mg/dL)
Exclusion criteria
* show symptoms of insomnia * smoke * have a personal history of stroke or diabetes * take birth control pills
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change From Wake in Central Aortic Pulse Pressure After 11 Hours in Bed | One night during each time in bed condition | Central aortic pulse pressure was measured one night during the week of 8 hours in bed, then again one night during the week of 11 hours in bed. Blood pressure was measured using an Oscar2 ambulatory blood pressure device. The device started recordings one hour prior to sleep and was programmed to take measurements once every 30 minutes during sleep until 10:00pm then every 45 minutes after 10:00pm until participants arose from bed. The change in central aortic pulse pressure from being awake to being asleep was compared between 8 and 11 hours in bed conditions. |
| Change in Cerebral Vascular Reactivity After 11 Hours in Bed | Morning after one week of 8 and 11 hours in bed | Blood flow measured in the middle cerebral artery during hypercapnia was measured after one week of 8 hours in bed, then again after one week of 11 hours in bed. Cerebral blood flow was measured using transcranial Doppler during 3 minutes of transient hypercapnia induced by rebreathing. Cerebral vascular reactivity was considered as the percent increase in cerebral blood flow at the end of 3 minutes of rebreathing relative to the Torr change in end-tidal carbon dioxide (percent change/Torr). |
| Change in Peak Reactive Hyperemia After 11 Hours in Bed | Morning after one week of 8 and 11 hours in bed | Peak forearm blood flow was measured after one week of 8 hours in bed, then again after one week of 11 hours in bed. Peak reactive hyperemia in the forearm (ml/100ml/min) was measured using venous occlusion plethysmography after 10 minutes of forearm ischemia resulting from blood pressure cuff inflation at the upper-arm. Peak blood flow was considered the highest blood flow measurement after the blood pressure cuff was deflated. |
| Change in Arterial Stiffness After 11 Hours in Bed | Morning after one week of 8 and 11 hours in bed | Arterial stiffness was measured after one week of 8 hours in bed, then again after one week of 11 hours in bed. Carotid-femoral pulse wave velocity was used as the measure of arterial stiffness. Radial arterial tonometry was used to derive a central aortic blood pressure wave. Wave separation analysis of the aortic pressure wave was then used to calculate pulse wave velocity from transit time and carotid-femoral path length. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Executive Function After Aerobic Exercise | Baseline and after exercise | Executive function was assessed using a Stroop color-word test that participants took using a computer with automated software (Automated Neuropsychological Assessment Metrics, known as ANAM). Score reported are number of correct answers. A higher score means a better outcome, in this case, better executive functioning. Participants took the Stoop color-word test after one week of 8 and 11 hours in bed (i.e., baseline) then the morning after one day of aerobic exercise. Exercise consisted of three sessions of 10 minutes brisk walking at a heart rate considered to be moderate intensity (50-70% of age-predicted maximal heart rate). Results reported reflect the change in score after exercise (morning after exercise minus baseline). |
| Change in Mental Flexibility After Aerobic Exercise | Baseline and after exercise | Mental flexibility was assessed using a Switching task that participants took on a computer with automated software (Automated Neuropsychological Assessment Metrics, known as ANAM). Scores reflect throughput scores which is a continuous variable that is the ratio of correct answers per minute during the Manikin test. Higher throughput scores mean better outcome, in this case, better mental flexibility. Participants took the Switching task after one week of 8 and 11 hours in bed (i.e., baseline) then the morning after one day of aerobic exercise. Exercise consisted of three sessions of 10 minutes brisk walking at a heart rate considered to be moderate intensity (50-70% of age-predicted maximal heart rate). Results reported reflect the change in throughput scores after exercise (morning after exercise minus baseline). |
| Change in Spatial Orientation After Aerobic Exercise | Baseline and after exercise | Score from a Manikin test of spatial orientation that participants took using a computer with automated software (Automated Neuropsychological Assessment Metrics, known as ANAM). Scores reflect throughput scores which is a continuous variable that is the ratio of correct answers per minute during the Manikin test. Higher throughput scores mean better outcome, in this case, better spatial orientation ability. Participants took the Manikin test after one week of 8 and 11 hours in bed (i.e., baseline) then the morning after one day of aerobic exercise. Exercise consisted of three sessions of 10 minutes brisk walking at a heart rate considered to be moderate intensity (50-70% of age-predicted maximal heart rate). Results reported reflect the change in throughput scores after exercise (morning after exercise minus baseline). |
Countries
United States
Participant flow
Recruitment details
34 participants were screened for eligibility between October 16, 2019 and May 24, 2021at Texas Tech University in Lubbock, TX.
Pre-assignment details
23 of 34 participants were randomized. Of those not randomized, 8 did not meet inclusion criteria and 3 declined to participate.
Participants by arm
| Arm | Count |
|---|---|
| 8, Then 11 Hours in Bed Participants were first asked to spend 8 hours in bed for one week. After 1 night of washout, participants were then asked to spend 11 hours in bed for one week. | 6 |
| 11, Then 8 Hours in Bed Participants were first asked to spend 11 hours in bed for one week. After 1 night of washout, participants were then asked to spend 8 hours in bed for one week. | 6 |
| Total | 12 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | discomfort with blood pressure cuff | 2 | 0 |
| Overall Study | felt tired after restricted time in bed | 3 | 0 |
| Overall Study | Protocol Violation | 0 | 4 |
| Overall Study | scheduling conflict | 1 | 1 |
Baseline characteristics
| Characteristic | 8, Then 11 Hours in Bed | 11, Then 8 Hours in Bed | Total |
|---|---|---|---|
| Age, Continuous | 48 years STANDARD_DEVIATION 6 | 43 years STANDARD_DEVIATION 3 | 45 years STANDARD_DEVIATION 5 |
| Body mass index | 26 kg/m^2 STANDARD_DEVIATION 3 | 24 kg/m^2 STANDARD_DEVIATION 5 | 26 kg/m^2 STANDARD_DEVIATION 4 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 6 Participants | 6 Participants | 12 Participants |
| Seated Diastolic Blood Pressure | 75 mm Hg STANDARD_DEVIATION 6 | 73 mm Hg STANDARD_DEVIATION 10 | 74 mm Hg STANDARD_DEVIATION 8 |
| Seated Systolic Blood Pressure | 118 mm Hg STANDARD_DEVIATION 10 | 111 mm Hg STANDARD_DEVIATION 8 | 114 mm Hg STANDARD_DEVIATION 9 |
| Sex: Female, Male Female | 5 Participants | 5 Participants | 10 Participants |
| Sex: Female, Male Male | 1 Participants | 1 Participants | 2 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 12 | 0 / 12 |
| other Total, other adverse events | 0 / 12 | 0 / 12 |
| serious Total, serious adverse events | 0 / 12 | 0 / 12 |
Outcome results
Primary
Change From Wake in Central Aortic Pulse Pressure After 11 Hours in Bed
Central aortic pulse pressure was measured one night during the week of 8 hours in bed, then again one night during the week of 11 hours in bed. Blood pressure was measured using an Oscar2 ambulatory blood pressure device. The device started recordings one hour prior to sleep and was programmed to take measurements once every 30 minutes during sleep until 10:00pm then every 45 minutes after 10:00pm until participants arose from bed. The change in central aortic pulse pressure from being awake to being asleep was compared between 8 and 11 hours in bed conditions.
Time frame: One night during each time in bed condition
Population: All participants who completed all study visits were included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change From Wake in Central Aortic Pulse Pressure After 11 Hours in Bed | -1.5 mm Hg | Standard Deviation 8.9 |
| 11hours in Bed | Change From Wake in Central Aortic Pulse Pressure After 11 Hours in Bed | 0.5 mm Hg | Standard Deviation 5.2 |
Comparison: Two-tailed paired t-tests were used to compare variables between time in bed conditions.p-value: 0.36t-test, 2 sided
Primary
Change in Arterial Stiffness After 11 Hours in Bed
Arterial stiffness was measured after one week of 8 hours in bed, then again after one week of 11 hours in bed. Carotid-femoral pulse wave velocity was used as the measure of arterial stiffness. Radial arterial tonometry was used to derive a central aortic blood pressure wave. Wave separation analysis of the aortic pressure wave was then used to calculate pulse wave velocity from transit time and carotid-femoral path length.
Time frame: Morning after one week of 8 and 11 hours in bed
Population: All participants who completed all study visits were included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change in Arterial Stiffness After 11 Hours in Bed | 6.84 m/s | Standard Deviation 0.64 |
| 11hours in Bed | Change in Arterial Stiffness After 11 Hours in Bed | 6.96 m/s | Standard Deviation 0.64 |
Comparison: Paired t-test used to compare carotid-femoral pulse wave velocity (index of arterial stiffness) between sleep protocols.p-value: 0.29t-test, 2 sided
Primary
Change in Cerebral Vascular Reactivity After 11 Hours in Bed
Blood flow measured in the middle cerebral artery during hypercapnia was measured after one week of 8 hours in bed, then again after one week of 11 hours in bed. Cerebral blood flow was measured using transcranial Doppler during 3 minutes of transient hypercapnia induced by rebreathing. Cerebral vascular reactivity was considered as the percent increase in cerebral blood flow at the end of 3 minutes of rebreathing relative to the Torr change in end-tidal carbon dioxide (percent change/Torr).
Time frame: Morning after one week of 8 and 11 hours in bed
Population: The middle cerebral artery could not be located in 3 participants, so data was analyzed in 9 participants that had complete data.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change in Cerebral Vascular Reactivity After 11 Hours in Bed | 11.9 percent change/Torr | Standard Deviation 2.8 |
| 11hours in Bed | Change in Cerebral Vascular Reactivity After 11 Hours in Bed | 11.3 percent change/Torr | Standard Deviation 1.8 |
Comparison: Paired t-test comparing the two time in bed protocols.p-value: 0.51t-test, 2 sided
Primary
Change in Peak Reactive Hyperemia After 11 Hours in Bed
Peak forearm blood flow was measured after one week of 8 hours in bed, then again after one week of 11 hours in bed. Peak reactive hyperemia in the forearm (ml/100ml/min) was measured using venous occlusion plethysmography after 10 minutes of forearm ischemia resulting from blood pressure cuff inflation at the upper-arm. Peak blood flow was considered the highest blood flow measurement after the blood pressure cuff was deflated.
Time frame: Morning after one week of 8 and 11 hours in bed
Population: All participants who completed all study visits were included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change in Peak Reactive Hyperemia After 11 Hours in Bed | 20.8 ml/100ml/min | Standard Deviation 5.8 |
| 11hours in Bed | Change in Peak Reactive Hyperemia After 11 Hours in Bed | 24.2 ml/100ml/min | Standard Deviation 7.2 |
Comparison: Paired t-test comparing peak forearm blood flow between sleep protocols.p-value: 0.03t-test, 2 sided
Secondary
Change in Executive Function After Aerobic Exercise
Executive function was assessed using a Stroop color-word test that participants took using a computer with automated software (Automated Neuropsychological Assessment Metrics, known as ANAM). Score reported are number of correct answers. A higher score means a better outcome, in this case, better executive functioning. Participants took the Stoop color-word test after one week of 8 and 11 hours in bed (i.e., baseline) then the morning after one day of aerobic exercise. Exercise consisted of three sessions of 10 minutes brisk walking at a heart rate considered to be moderate intensity (50-70% of age-predicted maximal heart rate). Results reported reflect the change in score after exercise (morning after exercise minus baseline).
Time frame: Baseline and after exercise
Population: All participants who completed all study visits were included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change in Executive Function After Aerobic Exercise | 4.5 correct answers | Standard Deviation 5.4 |
| 11hours in Bed | Change in Executive Function After Aerobic Exercise | 2.4 correct answers | Standard Deviation 6.8 |
Comparison: A two-way repeated measures ANOVA was used to evaluate the main effect of exercise (before vs. after exercise) on the number of correct answers during a Stroop color-word test.p-value: 0.04ANOVA
Secondary
Change in Mental Flexibility After Aerobic Exercise
Mental flexibility was assessed using a Switching task that participants took on a computer with automated software (Automated Neuropsychological Assessment Metrics, known as ANAM). Scores reflect throughput scores which is a continuous variable that is the ratio of correct answers per minute during the Manikin test. Higher throughput scores mean better outcome, in this case, better mental flexibility. Participants took the Switching task after one week of 8 and 11 hours in bed (i.e., baseline) then the morning after one day of aerobic exercise. Exercise consisted of three sessions of 10 minutes brisk walking at a heart rate considered to be moderate intensity (50-70% of age-predicted maximal heart rate). Results reported reflect the change in throughput scores after exercise (morning after exercise minus baseline).
Time frame: Baseline and after exercise
Population: All participants who completed all study visits were included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change in Mental Flexibility After Aerobic Exercise | 2.8 correct answers per minute | Standard Deviation 4.9 |
| 11hours in Bed | Change in Mental Flexibility After Aerobic Exercise | 1.6 correct answers per minute | Standard Deviation 3.3 |
Comparison: A two-way repeated measures ANOVA was used to evaluate the main effect of exercise (before vs. after exercise) on throughput scores from a Switching task.p-value: 0.02ANOVA
Secondary
Change in Spatial Orientation After Aerobic Exercise
Score from a Manikin test of spatial orientation that participants took using a computer with automated software (Automated Neuropsychological Assessment Metrics, known as ANAM). Scores reflect throughput scores which is a continuous variable that is the ratio of correct answers per minute during the Manikin test. Higher throughput scores mean better outcome, in this case, better spatial orientation ability. Participants took the Manikin test after one week of 8 and 11 hours in bed (i.e., baseline) then the morning after one day of aerobic exercise. Exercise consisted of three sessions of 10 minutes brisk walking at a heart rate considered to be moderate intensity (50-70% of age-predicted maximal heart rate). Results reported reflect the change in throughput scores after exercise (morning after exercise minus baseline).
Time frame: Baseline and after exercise
Population: All participants who completed all study visits were included in the analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| 8 Hours in Bed | Change in Spatial Orientation After Aerobic Exercise | 7.0 correct answers per minute | Standard Deviation 4.7 |
| 11hours in Bed | Change in Spatial Orientation After Aerobic Exercise | 3.9 correct answers per minute | Standard Deviation 5.6 |
Comparison: A two-way repeated measures ANOVA was used to evaluate the main effect of exercise (before vs. after exercise) on Manikin throughput scores.p-value: <0.001ANOVA