Sleep and Circadian Mechanisms of Non-dipping Blood Pressure

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.