Sleep
Conditions
Keywords
Sleep, Sleep restriction, Cognitive performance
Brief summary
This study aims to assess whether slow wave sleep enhancement using SmartSleep technology benefits daytime cognitive performance during periods of chronic sleep restriction.
Detailed description
Adequate healthy sleep is essential in spaceflight to ensure that astronauts maintain a high level of cognitive performance capability and do so without undue stress. There is a need for a technology that can improve sleep quality in space and biologically maximize the performance benefits of limited sleep duration, without unduly affecting the ability of astronauts to awaken abruptly and respond to an in-flight emergency. Sleep slow waves support system and synaptic consolidation by promoting specific patterns of neuromodulatory and electric activities, and subjective sleep quality is related to the size and number of slow waves that occur nightly. This study will use SmartSleep (Philips) technology to determine what effect the device has on daytime cognitive performance after emergent awakenings from sleep in a chronic sleep restriction paradigm. The SmartSleep technology uses two small sensors in the headband to continuously detect the brain's slow wave sleep (delta/theta frequency) in real time, and a closed-loop algorithm customizes the timing and volume of tones to optimize the sleep pattern. Thus, the device uses quiet audio tones (sub-awareness) to increase slow waves, which can enhance sleep quality/depth, thereby enhancing subsequent waking cognitive performance without the unwanted sedating effects of medications on cognitive functions during emergency awakenings. Subjects will be in the laboratory for 7 days/6 nights. Night 1 will be an adaptation night with 8-hours time in bed. Nights 2-5 will consist of 5 hours time in bed, followed by night 6 of a recovery 10 hours time in bed. During nights 2-5, subjects will receive one of four stimulation modalities using the SmartSleep wearable device. Subjects will receive all four modalities in a randomized order: 1. Continuous Fixed Interval 2. Block 3. In-Phase Adjustable 4. Sham: No auditory stimulation while wearing the SmartSleep headband Cognitive performance testing and self-report surveys will be completed on a daily basis. A total of 12 healthy astronaut-like adults will be studied. Subjects will complete the 7-day study in groups of 4.
Interventions
DEVICEPhilips SmartSleep Technology--Continuous Fixed Interval modality
During the 4 nights of sleep restriction (5 hours time in bed), subjects will have one of the following SmartSleep stimulation modalities each night in a randomized order. All subjects will receive all 4 stimulation modalities: 1. Continuous Fixed Interval 2. Block 3. In-Phase Adjustable 4. Sham: No auditory stimulation while wearing the SmartSleep headband
DEVICEPhilips SmartSleep Technology--Block modality
During the 4 nights of sleep restriction (5 hours time in bed), subjects will have one of the following SmartSleep stimulation modalities each night in a randomized order. All subjects will receive all 4 stimulation modalities: 1. Continuous Fixed Interval 2. Block 3. In-Phase Adjustable 4. Sham: No auditory stimulation while wearing the SmartSleep headband
DEVICEPhilips SmartSleep Technology--In-Phase Adjustable modality
During the 4 nights of sleep restriction (5 hours time in bed), subjects will have one of the following SmartSleep stimulation modalities each night in a randomized order. All subjects will receive all 4 stimulation modalities: 1. Continuous Fixed Interval 2. Block 3. In-Phase Adjustable 4. Sham: No auditory stimulation while wearing the SmartSleep headband
Sponsors
National Aeronautics and Space Administration (NASA)
Philips Healthcare
University of Wisconsin, Madison
University of Pennsylvania
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Masking description
The SmartSleep device will be programmed by investigators not involved in study execution. Subjects will wear the SmartSleep device each night and will be unaware of the order of stimulation modalities. In addition, both study personnel and those assessing outcomes will not be aware of the order of stimulation modalities.
Intervention model description
This study uses within subject randomization. Each subject will receive all of the 4 sleep conditions in a randomized order that will be unknown to the subject.
Eligibility
Sex/Gender
ALL
Age
30 Years to 55 Years
Healthy volunteers
Yes
Inclusion criteria
* Bachelor's degree or Master's degree (or the equivalent in work experience) in a relevant field, and/or military service. * Free of psychological/psychiatric conditions that preclude participation. * BMI \< 35. * Self-reported regular sleep schedule; able to maintain their sleep schedule during the course of the study. * Self-reported sleep duration of 6-8.5 hrs per night (verified by 6 work days of ambulatory sleep monitoring with wrist actigraphy and daily logs). * Ability to read/write English.
Exclusion criteria
* History of neurological, psychiatric, or other medical condition that excludes participation. * Current mania or psychosis. * Current depression as determined by the Beck Depression Inventory (Beck, 1996). * Alcohol or drug abuse in the past year based upon history and urine toxicology screen. * Excessive alcohol intake (≥ 21 drinks per week) or binge alcohol consumption (\> 5 drinks per day). * Excessive caffeine consumption (\> 650mg/day combining all caffeinated drinks regularly absorbed during the day). * Current smoker/tobacco user, or using nicotine replacement therapy. Those that have been nicotine-free for 30 days will be included. * Acute, chronic, or debilitating medical conditions, major Axis I psychiatric illness based on history, physical exam, blood and urine chemistries, and CBC. * Individuals who self-report a history of recurrent seizures or epilepsy or have a history of medical conditions that could increase the chance of seizures (e.g. stroke, aneurysm, brain surgery, structural brain lesion). * Cardiovascular, neurological, gastrointestinal, or musculoskeletal problems that exclude participation. * Major controlled or uncontrolled medical condition such as congestive heart failure, neuromuscular disease, renal failure, cancer, COPD, respiratory failure or insufficiency, or patients requiring oxygen therapy (as determined by self-report). * Currently working night, swing, split or rotating shift. * Current use or use of within the past month of a prescription or over-the-counter sleep medication or stimulant; use of psychoactive medication (based on self-report and review with a study clinician). * Pregnant or currently breast feeding * Prior history or diagnosis of any sleep disorder * High Risk of OSA based on STOP-BANG Questionnaire (yes on at least 4 of 8 questions) * High Risk of Restless Legs Syndrome (RLS) based on Cambridge-Hopkins Screening questionnaire * High Risk of Insomnia based on Insomnia Severity Index (score of 22 or higher) * Individuals who self-report severe contact dermatitis or allergy to silicone, nickel or silver. * Individuals who self-report moderate hearing loss. * Inability to achieve appropriate headband fit. * Planned travel across more than one time zone one month prior to and/or during the anticipated period of the study with SmartSleeps device use. * Intentional naps during the week.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Psychomotor Vigilance Test-Brief (PVT-B) | Days 3-6 | The PVT is a simple reaction time test that requires participants to react, as quickly as possible, by pressing a response key as soon as a rolling number counter presented in a box in the center of the computer screen appears. The PVT is a validated and widely-used measure of vigilant attention that is sensitive to the effects of sleep loss. The primary outcome was the number of PVT lapses. The minimum number of PVT lapses is 0 and there is no maximum number of lapses, which are defined as response times \>355 ms. More PVT lapses indicates worse performance. |
| Slow-wave Activity | Days 3-6 | Total delta power measured during sleep |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Digit Symbol Substitution Test (DSST) | Days 3-6 | The Digit Symbol Substitution Test (DSST) is a widely used measure of cognitive throughput and cognitive instability that is sensitive to the effects of sleep loss. The DSST was adapted from the Wechsler Adult Intelligence Scale. Participants are shown an array of symbols and with corresponding numbers on a keyboard. They are then presented the symbols one at a time in random order and must respond with the correct corresponding number as quickly as possible. The primary outcome was number correct and given the established practice effects on the DSST, this measure was corrected for practice effects. The DSST has a minimum of 0 correct responses and does not have a maximum; a higher number on the DSST represents better performance. |
| Descending Subtraction Task (DST) | Days 3-6 | The Descending Subtraction Test (DST) is a measure of working memory that is sensitive to the effects of sleep loss. The DST requires participants to mentally subtract numbers in a sequential fashion as quickly as possible. For example, if the starting number is 987, the participant subtracts nine from 987, with the difference being 978, the participant then subtracts eight from 978, and so on subtracting by seven, six, five, four, three, two, and one, from each difference at which point, and the participant then recycles the subtraction sequence beginning at nine again. The DST has a minimum of 0 correct responses and does not have a maximum; a higher number on the DST represents better performance. The primary outcome on the DST was Number correct. |
| Robotic On-Board Trainer (ROBoT) Task | Days 3-6 | The Robotic On-Board Trainer (ROBoT) task is NASA's platform for training astronauts to perform docking and grappling maneuvers using the Canada Arm. The system is based on highly realistic 3D simulations of the arm and associated physics. The ROBoT system involves a left-hand translational controller (x/y/z directions) and a right-hand rotational controller (pitch/roll/yaw), plus two laptop computer screens. Key performance metrics include: (i) docking position accuracy, (ii) docking orientation accuracy, (iii) total task time, and (iv) smoothness of approach trajectory, which are aggregated to generate the primary outcome, which is the mean weighted score . The weighted score ranges from 0 to 10 and a lower score indicates better performance. |
Countries
United States
Participant flow
Pre-assignment details
There are no pre-assignment events to report.
Participants by arm
| Arm | Count |
|---|---|
| SmartSleep Modality Assignment This study uses within subject comparison. For each subject, the order of SmartSleep modalities for each of the 4 nights of sleep restriction will be randomized. All subjects will receive all 4 stimulation modalities.
Philips SmartSleep Technology: During the 4 nights of sleep restriction (5 hours time in bed), subjects will have one of the following SmartSleep stimulation modalities each night in a randomized order. All subjects will receive all 4 stimulation modalities:
1. Continuous Fixed Interval
2. Block
3. In-Phase Adjustable
4. Sham: No auditory stimulation while wearing the SmartSleep headband | 8 |
| Total | 8 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Withdrawal by Subject | 1 |
Baseline characteristics
| Characteristic | SmartSleep Modality Assignment |
|---|---|
| Age, Continuous | 41.9 years STANDARD_DEVIATION 8.1 |
| PVT lapses of attention | 2.44 PVT lapses STANDARD_DEVIATION 4.98 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 5 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 3 Participants |
| Region of Enrollment United States | 8 participants |
| Sex: Female, Male Female | 2 Participants |
| Sex: Female, Male Male | 6 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 8 | 0 / 8 | 0 / 8 | 0 / 8 |
| other Total, other adverse events | 0 / 8 | 0 / 8 | 0 / 8 | 0 / 8 |
| serious Total, serious adverse events | 0 / 8 | 0 / 8 | 0 / 8 | 0 / 8 |
Outcome results
Primary
Psychomotor Vigilance Test-Brief (PVT-B)
The PVT is a simple reaction time test that requires participants to react, as quickly as possible, by pressing a response key as soon as a rolling number counter presented in a box in the center of the computer screen appears. The PVT is a validated and widely-used measure of vigilant attention that is sensitive to the effects of sleep loss. The primary outcome was the number of PVT lapses. The minimum number of PVT lapses is 0 and there is no maximum number of lapses, which are defined as response times \>355 ms. More PVT lapses indicates worse performance.
Time frame: Days 3-6
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| SmartSleep Modality Assignment | Psychomotor Vigilance Test-Brief (PVT-B) | Continuous Fixed Interval | 3.59 PVT lapses | Standard Deviation 8.18 |
| SmartSleep Modality Assignment | Psychomotor Vigilance Test-Brief (PVT-B) | Block | 4.61 PVT lapses | Standard Deviation 10.98 |
| SmartSleep Modality Assignment | Psychomotor Vigilance Test-Brief (PVT-B) | In-Phase Adjustable | 5.55 PVT lapses | Standard Deviation 13.02 |
| SmartSleep Modality Assignment | Psychomotor Vigilance Test-Brief (PVT-B) | Sham | 3.95 PVT lapses | Standard Deviation 9.11 |
Comparison: Number of lapses of attention were averaged across assessments within each day and the statistical analysis adjusted for baseline.p-value: 0.3695% CI: [-0.403, 1.06]Mixed Models Analysis
Comparison: Number of lapses of attention upon emergent awakeningp-value: 0.4995% CI: [-1.222, 0.608]Mixed Models Analysis
Primary
Slow-wave Activity
Total delta power measured during sleep
Time frame: Days 3-6
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| SmartSleep Modality Assignment | Slow-wave Activity | Block | 1006.00 microvolts^2 | Standard Deviation 421.5 |
| SmartSleep Modality Assignment | Slow-wave Activity | In-Phase Adjustable | 972.63 microvolts^2 | Standard Deviation 485.36 |
| SmartSleep Modality Assignment | Slow-wave Activity | SHAM | 822.38 microvolts^2 | Standard Deviation 370.59 |
| SmartSleep Modality Assignment | Slow-wave Activity | Continuous Fixed Interval | 943.13 microvolts^2 | Standard Deviation 311.2 |
p-value: 0.8795% CI: [-5.4, 6.31]Mixed Models Analysis
Secondary
Descending Subtraction Task (DST)
The Descending Subtraction Test (DST) is a measure of working memory that is sensitive to the effects of sleep loss. The DST requires participants to mentally subtract numbers in a sequential fashion as quickly as possible. For example, if the starting number is 987, the participant subtracts nine from 987, with the difference being 978, the participant then subtracts eight from 978, and so on subtracting by seven, six, five, four, three, two, and one, from each difference at which point, and the participant then recycles the subtraction sequence beginning at nine again. The DST has a minimum of 0 correct responses and does not have a maximum; a higher number on the DST represents better performance. The primary outcome on the DST was Number correct.
Time frame: Days 3-6
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| SmartSleep Modality Assignment | Descending Subtraction Task (DST) | Continuous Fixed Interval | 18.52 Correct responses | Standard Deviation 10.18 |
| SmartSleep Modality Assignment | Descending Subtraction Task (DST) | Block | 19.33 Correct responses | Standard Deviation 9.73 |
| SmartSleep Modality Assignment | Descending Subtraction Task (DST) | In-Phase Adjustable | 20.04 Correct responses | Standard Deviation 10.97 |
| SmartSleep Modality Assignment | Descending Subtraction Task (DST) | Sham | 18.84 Correct responses | Standard Deviation 9.41 |
Comparison: Number correct on the DST was averaged across DST administrations within each day and adjusted for baseline.p-value: 0.7695% CI: [-0.919, 0.678]Mixed Models Analysis
Secondary
Digit Symbol Substitution Test (DSST)
The Digit Symbol Substitution Test (DSST) is a widely used measure of cognitive throughput and cognitive instability that is sensitive to the effects of sleep loss. The DSST was adapted from the Wechsler Adult Intelligence Scale. Participants are shown an array of symbols and with corresponding numbers on a keyboard. They are then presented the symbols one at a time in random order and must respond with the correct corresponding number as quickly as possible. The primary outcome was number correct and given the established practice effects on the DSST, this measure was corrected for practice effects. The DSST has a minimum of 0 correct responses and does not have a maximum; a higher number on the DSST represents better performance.
Time frame: Days 3-6
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| SmartSleep Modality Assignment | Digit Symbol Substitution Test (DSST) | Continuous Fixed Interval | 61.02 Correct responses | Standard Deviation 11.72 |
| SmartSleep Modality Assignment | Digit Symbol Substitution Test (DSST) | Block | 61.73 Correct responses | Standard Deviation 11.05 |
| SmartSleep Modality Assignment | Digit Symbol Substitution Test (DSST) | In-Phase Adjustable | 58.55 Correct responses | Standard Deviation 17.68 |
| SmartSleep Modality Assignment | Digit Symbol Substitution Test (DSST) | Sham | 61.01 Correct responses | Standard Deviation 12.41 |
Comparison: Number correct on the DSST was averaged across DSST administrations within each day and was adjusted for baseline performance.p-value: 0.8995% CI: [-1.767, 1.543]Mixed Models Analysis
Secondary
Robotic On-Board Trainer (ROBoT) Task
The Robotic On-Board Trainer (ROBoT) task is NASA's platform for training astronauts to perform docking and grappling maneuvers using the Canada Arm. The system is based on highly realistic 3D simulations of the arm and associated physics. The ROBoT system involves a left-hand translational controller (x/y/z directions) and a right-hand rotational controller (pitch/roll/yaw), plus two laptop computer screens. Key performance metrics include: (i) docking position accuracy, (ii) docking orientation accuracy, (iii) total task time, and (iv) smoothness of approach trajectory, which are aggregated to generate the primary outcome, which is the mean weighted score . The weighted score ranges from 0 to 10 and a lower score indicates better performance.
Time frame: Days 3-6
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| SmartSleep Modality Assignment | Robotic On-Board Trainer (ROBoT) Task | Continuous Fixed Interval | 5.61 units on a scale | Standard Deviation 2.09 |
| SmartSleep Modality Assignment | Robotic On-Board Trainer (ROBoT) Task | Block | 5.70 units on a scale | Standard Deviation 1.83 |
| SmartSleep Modality Assignment | Robotic On-Board Trainer (ROBoT) Task | In-Phase Adjustable | 6.44 units on a scale | Standard Deviation 2.14 |
| SmartSleep Modality Assignment | Robotic On-Board Trainer (ROBoT) Task | Sham | 5.73 units on a scale | Standard Deviation 2.38 |
Comparison: The mean weighted score on the ROBoT was adjusted for baseline.p-value: 0.6495% CI: [-0.286, 0.456]Mixed Models Analysis