BackgroundThe relationship between the sleep/wake habits and the academic performance of medical students is insufficiently addressed in the literature. This study aimed to assess the relationship between sleep habits and sleep duration with academic performance in medical students.MethodsThis study was conducted between December 2009 and January 2010 at the College of Medicine, King Saud University, and included a systematic random sample of healthy medical students in the first (L1), second (L2) and third (L3) academic levels. A self-administered questionnaire was distributed to assess demographics, sleep/wake schedule, sleep habits, and sleep duration. Daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS). School performance was stratified as “excellent” (GPA ≥3.75/5) or “average” (GPA <3.75/5).ResultsThe final analysis included 410 students (males: 67%). One hundred fifteen students (28%) had “excellent” performance, and 295 students (72%) had “average” performance. The “average” group had a higher ESS score and a higher percentage of students who felt sleepy during class. In contrast, the “excellent” group had an earlier bedtime and increased TST during weekdays. Subjective feeling of obtaining sufficient sleep and non-smoking were the only independent predictors of “excellent” performance.ConclusionDecreased nocturnal sleep time, late bedtimes during weekdays and weekends and increased daytime sleepiness are negatively associated with academic performance in medical students.

Study design: Case-Control Study Objectives: To analyse global sagittal alignment including the cranial center of mass (CCOM) and proximal junctional kyphosis (PJK) in Adolescent Idiopathic Scoliosis (AIS) patients treated with posterior instrumentation. Summary of background data: PJK plays an important role in the global sagittal alignment in AIS patients. Maintaining the head above the pelvis allows for a minimization of energy expense in ambulation and upright posture. Numerous studies have been performed to understand PJK phenomena in AIS patients. However, to our knowledge, no study performed on AIS patients included the head in the analysis of global sagittal alignment and PJK. Methods: This study included 85 AIS patients and 51 asymptomatic adolescents. Low-dose bi-planar X-rays were acquired for each subject preoperatively and at two years follow up. Two global sagittal alignment parameters were calculated, i.e. the angle between the vertical and the line joining the center of the bi-coxofemoral axis (HA) and either the most superior point of the dentiform apophysis of C2 (OD) or the cranial center of mass (CCOM). Results: Among normal adolescents, the average OD-HA and CCOM-HA angles were-2.3°±2° and-1.5°±1.8°, respectively. Among AIS patients the average OD-HA and CCOM-HA angles were respectively-2.3°±1.9° and-1.3°±1.8° preoperatively and-2.8°±1.7° and-1.9°±1.7° at the last follow up. 13% of the patients developed PJK postoperatively. Case-bycase analysis showed that adjusting the thoracic kyphosis and the compensations required to maintain this constant could provide explanatory elements. Conclusions: OD-HA and CCOM-HA angles remain almost constant among normal group and patients, pre-and post-operatively, whether PJK or non-PJK. Five patients without PJK and only one patient with PJK produced abnormal values relative to the asymptomatic subjects. Therefore, PJK could be a compensation mechanism, which allows for CCOM-HA and, to a lesser extent, OD-HA to remain invariant.