Abstract
Background- The incidence of syncope exhibits a daily pattern with more occurrences in the morning, possibly as a result of influences from the endogenous circadian system and/or the daily pattern of behavioral/emotional stimuli. This study tested the hypothesis that the circadian system modulates cardiovascular responses to postural stress, leading to increased susceptibility to syncope at specific times of day. Methods and Results- Twelve subjects underwent a 13-day in-laboratory protocol in which subjects sleep-wake cycles were adjusted to 20 hours for 12 cycles. A 15-minute tilt-table test (60° head-up) was performed 4.5 hours after scheduled awakening in each cycle so that 12 tests in each subject were distributed evenly across the circadian cycle. Of 144 tests, signs/symptoms of presyncope were observed in 21 tests in 6 subjects. These presyncope events displayed a clear circadian rhythm (P=0.028) with almost all cases (17/21) occurring in the half of the circadian cycle corresponding to the biological night (10:30 PM to 10:30 AM). Significant circadian rhythms were also observed in hemodynamic and autonomic function markers (blood pressure, heart rate, epinephrine, norepinephrine, and indices of cardiac vagal tone) that may underlie the circadian rhythm of presyncope susceptibility. Conclusions-The circadian system affects cardiovascular responses to postural stress, resulting in greater susceptibility to presyncope during the night. This finding suggests that night-shift workers and people with disrupted sleep at night may have greater risk of syncope as a result of their exposure to postural stress during the biological night.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 961-970 |
| Number of pages | 10 |
| Journal | Circulation |
| Volume | 123 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 8 2011 |
| Externally published | Yes |
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Keywords
- cardiovascular response
- circadian rhythm
- syncope
ASJC Scopus subject areas
- Physiology (medical)
- Cardiology and Cardiovascular Medicine
Cite this
Endogenous circadian rhythm in vasovagal response to head-up tilt. / Hu, Kun; Scheer, Frank A J L; Laker, Michael; Smales, Carolina; Shea, Steven.
In: Circulation, Vol. 123, No. 9, 08.03.2011, p. 961-970.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Endogenous circadian rhythm in vasovagal response to head-up tilt
AU - Hu, Kun
AU - Scheer, Frank A J L
AU - Laker, Michael
AU - Smales, Carolina
AU - Shea, Steven
PY - 2011/3/8
Y1 - 2011/3/8
N2 - Background- The incidence of syncope exhibits a daily pattern with more occurrences in the morning, possibly as a result of influences from the endogenous circadian system and/or the daily pattern of behavioral/emotional stimuli. This study tested the hypothesis that the circadian system modulates cardiovascular responses to postural stress, leading to increased susceptibility to syncope at specific times of day. Methods and Results- Twelve subjects underwent a 13-day in-laboratory protocol in which subjects sleep-wake cycles were adjusted to 20 hours for 12 cycles. A 15-minute tilt-table test (60° head-up) was performed 4.5 hours after scheduled awakening in each cycle so that 12 tests in each subject were distributed evenly across the circadian cycle. Of 144 tests, signs/symptoms of presyncope were observed in 21 tests in 6 subjects. These presyncope events displayed a clear circadian rhythm (P=0.028) with almost all cases (17/21) occurring in the half of the circadian cycle corresponding to the biological night (10:30 PM to 10:30 AM). Significant circadian rhythms were also observed in hemodynamic and autonomic function markers (blood pressure, heart rate, epinephrine, norepinephrine, and indices of cardiac vagal tone) that may underlie the circadian rhythm of presyncope susceptibility. Conclusions-The circadian system affects cardiovascular responses to postural stress, resulting in greater susceptibility to presyncope during the night. This finding suggests that night-shift workers and people with disrupted sleep at night may have greater risk of syncope as a result of their exposure to postural stress during the biological night.
AB - Background- The incidence of syncope exhibits a daily pattern with more occurrences in the morning, possibly as a result of influences from the endogenous circadian system and/or the daily pattern of behavioral/emotional stimuli. This study tested the hypothesis that the circadian system modulates cardiovascular responses to postural stress, leading to increased susceptibility to syncope at specific times of day. Methods and Results- Twelve subjects underwent a 13-day in-laboratory protocol in which subjects sleep-wake cycles were adjusted to 20 hours for 12 cycles. A 15-minute tilt-table test (60° head-up) was performed 4.5 hours after scheduled awakening in each cycle so that 12 tests in each subject were distributed evenly across the circadian cycle. Of 144 tests, signs/symptoms of presyncope were observed in 21 tests in 6 subjects. These presyncope events displayed a clear circadian rhythm (P=0.028) with almost all cases (17/21) occurring in the half of the circadian cycle corresponding to the biological night (10:30 PM to 10:30 AM). Significant circadian rhythms were also observed in hemodynamic and autonomic function markers (blood pressure, heart rate, epinephrine, norepinephrine, and indices of cardiac vagal tone) that may underlie the circadian rhythm of presyncope susceptibility. Conclusions-The circadian system affects cardiovascular responses to postural stress, resulting in greater susceptibility to presyncope during the night. This finding suggests that night-shift workers and people with disrupted sleep at night may have greater risk of syncope as a result of their exposure to postural stress during the biological night.
KW - cardiovascular response
KW - circadian rhythm
KW - syncope
UR - http://www.scopus.com/inward/record.url?scp=79952734878&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79952734878&partnerID=8YFLogxK
U2 - 10.1161/CIRCULATIONAHA.110.943019
DO - 10.1161/CIRCULATIONAHA.110.943019
M3 - Article
VL - 123
SP - 961
EP - 970
JO - Circulation
JF - Circulation
SN - 0009-7322
IS - 9
ER -