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Abstract: FR-PO541

The Effect of Night-Time versus Sleep-Time on Blood Pressure Dipping

Session Information

Category: Hypertension

  • 1106 Hypertension: Clinical and Translational - Secondary Causes


  • Onder, Ali Mirza, Le Bonheur Children's Hospital, Memphis, Tennessee, United States
  • Onder, Songul, University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Jones, Tamekia, University of Tennessee Health Science Center, Memphis, Tennessee, United States

There is limited information on the sleep blood pressure profiles and sleep related blood pressure dipping (BPD) for subjects who work at night-time and sleep at daytime.


84 medical professionals are evaluated with 24 hour ambulatory blood pressure monitoring (ABPM) during three work- sleep schedules; work daytime and sleep at night-time, work night-time and sleep at daytime, and awake at daytime and sleep at night-time during an off-work day.
Subjects were divided into four distinct groups: subjects who only work at daytime and always sleep at night-time (Group A), subjects who switch from working day to night-time in frequent intervals such as every 3-4 days(Group B) or prolonged intervals such as every 3-4 months(Group C) and subjects who only work at night-time and always sleep during daytime(Group D).
Sleep score is defined as the product of the sleep BPD percentage and duration of sleep in hours. The Kruskal Wallis test was used to compare differences among groups, and the Signed rank test was used to evaluate paired differences.


Average reported sleep duration was indifferent between the four groups for both periods of work schedule. Although the median BPD profile (15.5 vs 12) and sleep score (112 vs 90) were higher for Group A than Group D, the differences were not statistically significant (p=0.31 and p=0.24). Groups B&C were compared for daytime and night-time work BPD; there was no difference for sleep BPD between two different work times (p=0.47). However, the median sleep score was significantly better when subjects were sleeping at night-time (127.5 vs 103, P=0.02). When the four groups were compared for their BPD during an off-work day, there was no difference for sleep BPD (p=0.43) and for sleep score (p=0.36).


In this preliminary study, the blood pressure dipping was predominantly associated with sleep time rather than night-time. Subjects who work at night had similar sleep BPD compared to subjects who work at daytime. However, subjects who switch shifts achieved a significantly higher sleep score when they slept at night-time, due to longer duration of sleep. The history of night-time work did not affect the sleep BPD on an off-work day, sleeping at night for any of the groups.