Long Sleep Duration and Vascular Function

Not Applicable

Completed

Conditions: Sleep

Interventions: Behavioral: Sleep duration

Registration Number: NCT04679051

Lead Sponsor: Texas Tech University

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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 23

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
8 hours time in bed	Sleep duration	Participants will be asked to spend 8 hours time in bed with the aim of achieving one week of normal sleep duration (7 to 8 hours).
11 hours time in bed	Sleep duration	Participants will be asked to spend 11 hours time in bed with the aim of achieving one week of long duration sleep as defined as 9+ hours of sleep.

Primary Outcome Measures

Name	Time	Method
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 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.
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.

Secondary Outcome Measures

Name	Time	Method
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).
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 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).