Sleep and Circadian Mechanisms of Non-dipping Blood Pressure

Sleep and Circadian Mechanisms Contributing to Nocturnal Non-dipping Blood Pressure

This study will be the first to distinguish the relative contributions of sleep, circadian and behavioral mechanisms to the non-dipping BP profile in Black adults and will lay the groundwork for optimizing therapies dependent on mechanisms, such as targeting sleep, targeting circadian rhythmicity, or targeting behaviors, and raising the possibility that ideal therapy for hypertension (HTN) may differ by race. This research will ultimately help to improve health and survival in black populations with HTN.

By studying standardized behaviors and regulators of BP during sleep and behavioral stresses across all circadian phases, this protocol will allow us specifically to:

1. To determine if poor sleep, while controlling for circadian phase, contributes to the higher overall BP and reduced nocturnal drop in BP in Blacks compared to Whites.
2. To determine if reduced BP responses to standardized behavioral changes across the day and night contribute to the higher overall BP and reduced nocturnal drop in BP in Blacks compared to Whites.
3. To determine if reduced circadian amplitude of BP contributes to the higher overall BP and reduced nocturnal drop in BP in Blacks compared to Whites.

Inclusion Criteria:

• Self-identified Black or White
• 'normotensive' (resting systolic blood pressure (SBP) <140/90 mmHg) or uncomplicated stage 1 'hypertensive' (systolic BP between 140 and 160 mmHg or a diastolic (DBP) between 90 and 100 mmHg).
• free of all prescription and non-prescription drugs (including caffeine, nicotine, alcohol and herbal medications)

Exclusion Criteria:

• Currently treated with pharmacologic agents for hypertension
• Blood pressure >160/100 mmHg
• Smoked within the last year
• Regular night work or rotating shift work for the three months prior to the study
• Travel across more than three time zones during the three months prior to the study.
• Any acute, chronic or debilitating medical conditions, other than mild hypertension (140<SBP<160 or 90<DBP<100 mmHg) and severe renal disease (glomerular filtration rate <30)
• Moderate to severe obstructive sleep apnea (OSA)
• History of severe psychiatric illnesses or psychiatric disorders will be excluded, including alcoholism, drug dependency, major depression, manic depressive illness, schizophrenic disorders, panic disorder, generalized anxiety disorder, post-traumatic stress disorder, agoraphobia, claustrophobia, paranoid personality disorder, schizoid personality disorder, schizotypal personality disorder, borderline personality disorder, and antisocial personality disorder.