Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT03895710 |
| Other study ID # |
CREC2015.701 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
February 1, 2016 |
| Est. completion date |
December 1, 2021 |
Study information
| Verified date |
March 2022 |
| Source |
Chinese University of Hong Kong |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
Our research question is: Are changes in sleep duration that occur naturally over school
holidays associated with changes in blood pressure (BP) in sleep-deprived adolescents?
In this study, the investigators will take advantage of changes in sleep duration that occur
during school holidays in adolescents who are sleep deprived (>6 months' history of sleeping
<8 hours per night during school term). The investigators will monitor the changes in
ambulatory BP and sleep duration over a period of 3 weeks which consist of a week at school,
followed by a week of holiday when natural sleep extension takes place, and then another week
of school after the holiday. Sleep-wake cycle will be recorded throughout the whole study
period with actigraphy and sleep diary. Twenty-four hour ambulatory BP monitoring will be
performed on the same weekday during each study week, when salivary cortisol will also be
collected. The primary outcome measure is the difference in ambulatory BP parameters between
school term and holiday. A control group without sleep deprivation (history of sleeping >8
hours per night) will also be studied concurrently
It is hypothesized that changes in sleep duration are negatively associated with changes in
BP. If this study confirms our hypothesis, sleep extension can be used as a relatively
inexpensive and simple behavioural intervention in the management and prevention of blood
pressure abnormalities. More importantly positive results from this project will provide
background information on which government and local school policy can be based and altered
for the betterment of our youths.
Description:
This is a cohort study that consists of 4 visits over a 3-week study period that includes two
periods of 7-day school attendance and one period of 7-day school holiday (Study design flow
chart). Subjects who have undergone physical examination and completed the screening
questionnaire, and are found to meet all the inclusion and none of the exclusion criteria
will be recruited. The first study week will be during school days, followed by a week of
school holiday, and the final week is when the subject returns back to school after the
holiday. The 3 periods need not to be consecutive so as to allow more flexibility to cater
for the subjects' schedule. All assessments however have to be completed within 60 days to
minimize the effects of growth on BP / sleep pattern.
Screening
During screening examination, participants will undergo a series of anthropometric
measurements. The body build of the subject will be assessed using standard procedures.
Standing height (in metres) will be measured without shoes using a Harpenden Stadiometer
(Holtain, UK). Body weight will be measured by an electronic weighing scale (Tanita BF-522,
Japan). Waist and hip circumference (in centimetres) will also be obtained. Body mass index
and waist circumference will be converted into z score using local reference. Blood pressure
will be taken using the Datascope Accutorr Plus. Two measurements are taken at 1-minute
intervals, with a third reading taken 5 minutes later if the difference between the first two
>4 mmHg. The average of two repeatable readings (difference ≤4 mmHg) will be used. Sexual
maturity rating will be evaluated by a validated gender specific self-assessment
questionnaire. Subjects will have to fill in a sleep questionnaire asking about their sleep
habits and symptoms, pediatric daytime sleepiness scale (PDSS), Epworth sleepiness scale
(ESS), and strength and difficulties questionnaire (SDQ). Information on parental medical
history will also be obtained from the parents using a medical history questionnaire. The
school calendar of each participant will also be obtained.
Collection of Data
Sleep pattern will be monitored by actigraphy together with sleep diary throughout the whole
study period. Twenty four-hour ambulatory BP monitoring and neurocognitive tests will be
performed on the last day of each study week. All BP monitoring and neurocognitive tests will
be performed during weekdays instead of weekends to avoid the possible weekend effect on
sleep pattern and outcomes. Saliva samples will also be collected in the evening and the
morning when the subjects are wearing the BP monitor for assessing cortisol awakening
response.
Actigraphy
On day 1 of the first week of study, participants will attend our sleep laboratory to start
actigraph recording (Actiwatch spectrum device; Phillips Respironics, Murrysville, PA; on
their non-dominant wrist) and will be instructed on how to complete the sleep diary.
Participants will have to wear the device until the end of the study period. Actigraphs will
be configured to collect information in 1-minute epochs by using a medium sensitivity
threshold, which has high sensitivity for detecting sleep compared with polysomnography.
Self-reported bedtimes and wake times will be used to score actigraph data using established
procedures. Variables of interest include actigraph-defined sleep period (ie, the period
between scored sleep onset and scored final awakening), actigraph scored sleep (minutes of
scored sleep within the actigraph-defined sleep period), wake after sleep onset (minutes of
scored wake within the actigraph-defined sleep period), and sleep efficiency (actigraph
scored sleep/actigraph-defined sleep period). The activity level during wakefulness will also
be extracted as a covariate for statistical analysis, as it may affect both sleep pattern and
BP.
Twenty four-hour ambulatory blood pressure monitoring
A validated oscillometric monitor (SpaceLabs 90217, SpaceLabs Medical, Redmond, Washington,
USA) will be used. Systolic, diastolic and mean arterial BP will be measured every 30
minutes. The exact cut-off time dividing wake and sleep BP will be defined individually
according to actigraphy. Recordings are included in the analysis when there is a minimum of
40 successful readings for the 24-hour period with a minimum of 1 successful reading per
hour. Individual mean systolic, diastolic and mean arterial BP are calculated for wake and
sleep periods. These BP data will be converted to z scores using the local "LMS" reference
values (with reference to gender and height). Subjects will be defined as hypertensive if
their systolic or diastolic BP is ≥95th percentile (z score ≥1.645).
Neurocognitive tests
Conners' Continuous Performance Test (CPT)
CPT-II (Ver. 5.2 for Windows®) is designed as a computer game-like test for the evaluation of
sustained attention and response inhibition for respondents aged 6 or above. Subjects are
required to press the space bar or click the mouse whenever any letter except the letter 'X'
appears on the computer screen. The test requires about 14 minutes to complete, and it will
be administered in the morning in a quiet room.
Trail-making Test Part A & B (Executive function)
The Trail-making test is composed of two parts which assess test-takers in attention, visual
scanning, speed of eye-hand coordination, information processing and set switching of
executive functions. Part A required subjects to connect sequentially 25 encircled numbers
which are randomly scattered over the test sheet. Similarly, for Part B, subjects are asked
connect encircled numbers (1-13) and alphabets (A-L) alternately in ascending patterns, i.e.
1-A-2-B-C. Any mistakes made throughout the test are pointed out by examiner immediately.
Thus, the scores of the tests are the time taken to complete the task.
Stroop Test-Victoria Version (Executive function)
This test captures cognitive flexibility and inhibition of executive functioning by three
successive tasks with increasing demands. It consists of three sets of stimulus cards (1)
colored dots, (2) common words printed in same colors as dots, and (3) color words printed in
non-corresponding colors of ink. For the first task, subjects are asked to simply name the
color of the dots in maximum speed as possible. For the second task, subjects are asked to
identify the color of ink each word is printed in, not to identify the word itself. For the
third task, subjects are asked to identify the color of ink each of the color words is
printed in, not to read the color word presented. Number of errors and time to perform the
task are recorded for each trial. The Chinese Victoria Version of the Stroop Test is
translated and validated by Dr. Tatia Lee and Dr. Kai Wang from the Laboratory of
Neuropsychology, the University of Hong Kong.
Raven's Standard Progressive Matrices Test (Nonverbal reasoning)
The Test is a nonverbal measure of general ability that uses nonverbal stimuli including
visual patterns and shapes to asses reasoning by analogy. It contains five sets with 12
problems in each set. Each question is a puzzle with a missing part; subjects are asked to
identify the most appropriate piece from six similar options. Children of age 5 years 6
months to 8 years 5 months can do a shortened version with only Set A, B, and C to allow
better control of test administration. Each set starts with a problem and develops a theme
that build on previous questions and become progressively more difficult. The test is
administered in a paper and pen format. While it is an open-ended session, most people
complete the test in less than 40 minutes.
Grooved Pegboard (Visual-motor coordination)
It is a manipulative dexterity test aim at assessing visual-motor coordination. It consists
of 25 holes with randomly positioned slots. Subjects are asked to place pegs, which have a
key along one side, into the holes from left to right. The task is performed once with
dominant hands and once with non-dominant hands. Subjects are advised to complete the task as
fast as possible. Subjects from 5 years old to 8 years 12 months will use a Kiddie version of
the test in which only the first two rows (10 pegs) of the pegboard are needed to complete.
Time taken, number of pegs placed on the pegboard, and number of dropped pegs are recorded to
assess the score of fine-motor coordination.
Cortisol awakening response (CAR)
Saliva samples will be collected with Salivette tubes for assessing the level of cortisol and
cortisone, as a reflection of stress which on its own can influence both sleep pattern and
BP.
Participants will be asked to collect their saliva in the morning. Each subject will have to
provide five saliva samples according to a fixed sampling protocol: (1) one hour before
bedtime, (2) immediately after awakening, (3) 15 min after awakening, (4) 30 min after
awakening, and (5) 45 min after awakening. Salivary cortisol and cortisone concentrations in
these samples will be measured by a liquid chromatography tandem mass spectrometry method at
the Biomedical Mass Spectrometry Unit, Department of Chemical Pathology, Prince of Wales
Hospital. Between-batch precision performance of the method has coefficients of variation of
<5%. The lower limits of quantitation are <0.5 nmol/l.
