Ahmed S. BaHammam

Metabolic, Endocrine, and Immune Consequences of Sleep Deprivation

Over the last three to four decades, it has been observed that the average total hours of sleep have decreased to less than seven hours per person per night. Concomitantly, global figures relating to obesity and diabetes mellitus have increased in an alarming fashion in adults and children, and it has been hypothesized that neuro-hormonal changes accompanying this behavioral sleep deprivation may lead to insulin resistance and, subsequently, to diabetes mellitus. Sleep deprivation has been associated with multiple physiological changes, including increased cortisol and ghrelin levels, decreased leptin levels and impaired glucose metabolism. Experimental studies have also shown an increase in inflammatory and pro-inflammatory markers, which are indicators of body stress, under sleep deprivation. This review elaborates further on this hypothesis, exploring the molecular basis for the link between both entities and the underlying pathophysiology that results in insulin resistance and diabetes mellitus. We review the results of experimental and epidemiological studies, specifically examining the relationship between sleep duration and the immune and endocrine systems.

Sleep and circadian rhythm dysregulation in schizophrenia

Sleep-onset and maintenance insomnia is a common symptom in schizophrenic patients regardless of either their medication status (drug-naive or previously treated) or the phase of the clinical course (acute or chronic). Regarding sleep architecture, the majority of studies indicate that non-rapid eye movement (NREM), N3 sleep and REM sleep onset latency are reduced in schizophrenia, whereas REM sleep duration tends to remain unchanged. Many of these sleep disturbances in schizophrenia appear to be caused by abnormalities of the circadian system as indicated by misalignments of the endogenous circadian cycle and the sleep-wake cycle. Circadian disruption, sleep onset insomnia and difficulties in maintaining sleep in schizophrenic patients could be partly related to a presumed hyperactivity of the dopaminergic system and dysfunction of the GABAergic system, both associated with core features of schizophrenia and with signaling in sleep and wake promoting brain regions. Since multiple neurotransmitter systems within the CNS can be implicated in sleep disturbances in schizophrenia, the characterization of the neurotransmitter systems involved remains a challenging dilemma.

Circadian pattern of sleep, energy expenditure, and body temperature of young healthy men during the intermittent fasting of Ramadan

We hypothesize that factors other than a sudden shift in eating habits contribute to delay of circadian rhythms during Ramadan. We assessed circadian changes during a baseline period (BL, 1 week before Ramadan), the first week (R1), and the second week (R2), of Ramadan, in six healthy Muslim young adults using portable armband physiological and activity sensor devices. All participants lived in an unconstrained environment and showed delayed sleep phase syndrome, so that they normally slept during the day and ate at night. During Ramadan, there was a further delay in the acrophase of skin temperature during Ramadan, indicating a shift in the circadian pattern of body temperature. Additionally, there was a delay in the peak of energy expenditure during R1 and R2. These results support our hypothesis that in addition to sudden shift in meal times, other factors may affect the sleep pattern and circadian rhythms during Ramadan.

The relationship between sleep and wake habits and academic performance in medical students: a cross-sectional study

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.

Comparison of Nasal Prong Pressure and Thermistor Measurements for Detecting Respiratory Events during Sleep

Introduction and Objectives: Thermistor (TH) measurements have been traditionally used to determine airflow during polysomnographic studies (PSG). However, low accuracy in detecting hypopneas is a major drawback. Nasal prong pressure (NPP) measurements are becoming increasingly popular for quantifying respiratory events during sleep. We prospectively compared NPP and TH measurements with respect to their ability to detect respiratory events during routine PSG. Methods: Forty consecutive patients (26 male, 14 female) with clinically suspected sleep-disordered breathing (SDB) underwent routine diagnostic PSG. Airflow was measured using NPP and TH devices simultaneously. PSG was scored manually according to R and K criteria. Respiratory events were scored in two passes. During the first pass, the TH signal was disabled and the NPP signal was scored. During the second pass, the NPP signal was disabled and the TH signal was scored. Scorers for one method were blinded from the results of the other method. To assess respiratory events, we used the respiratory arousal index (RAI), which was defined as the number of apneas and/or hypopneas followed by an arousal per hour of sleep, as detected by TH (RAI-TH) or NPP (RAI- NPP). Agreement analysis of the results obtained using the two different techniques was performed using the methodology of Bland-Altman. Results: Twenty-six patients had obstructive sleep apnea, 10 had respiratory effort-related arousals and 4 had habitual snoring. The failure time of the flow signal on the raw data was not different between the two methods (NPP: 6 ± 13 min, TH: 4 ± 7 min). The Bland-Altman analysis of RAIs demonstrated that more events were nearly always detected using NPP compared to TH devices (44.4 ± 37 vs. 35.4 ± 31, p < 0.001). No difference in the index of central apneas between the two methods could be detected. Sleep position had no effect on either measurement method. Conclusions: NPP measurements are superior to TH measurements for detecting obstructive respiratory events during sleep. Measurement of NPP is a simple, practical, sensitive and reliable method for detecting the whole spectrum of SDB. We recommend incorporating nasal prongs in routine polysomnographic monitoring.

Sleep estimation using BodyMedia's SenseWear™ armband in patients with obstructive sleep apnea

OBJECTIVES: We aimed to evaluate the validity of the BodyMedias SenseWear™ Armband (BSA) device in estimating total sleep time (TST) in patients with obstructive sleep apnea (OSA). METHODS: Simultaneous overnight recordings of in-laboratory polysomnography (PSG) and BSA were performed on (1) 107 OSA patients (mean age of 45.2 ± 14.3 years, mean apnea hypopnea index of 43 ± 35.7/hr and (2) 30 controls matched with OSA patients for age and body mass index. An agreement analysis between the PSG and BSA scoring results was performed using the Bland and Altman method. RESULTS: There was no significant difference in OSA patients between BSA and PSG with regard to TST, total wake time, and sleep efficiency. There was also no significant difference in the controls between BSA and PSG with regard to TST, total wake time, and sleep efficiency. Bland Altman plots showed strong agreement between TST, wake time, and sleep efficiency for both OSA and the controls. The intraclass correlation coefficients revealed perfect agreement between BSA and PSG in different levels of OSA severity and both genders. CONCLUSION: The current data suggest that BSA is a reliable method for determining sleep in patients with OSA when compared against the gold standard test (PSG). BSA can be a useful tool in determining sleep in patients with OSA and can be combined with portable sleep studies to determine TST.

Sleep in acute care units.

Patients in the acute care units (ACU) are usually critically ill, making them more susceptible to the unfavorable atmosphere in the hospital. One of these unfavorable factors is sleep disruption and deprivation. Many factors may affect sleep in the ACU, including therapeutic interventions, diagnostic procedures, medications, the underlying disease process, and noise generated in the ACU environment. Many detrimental physiological effects can occur secondary to noise and sleep deprivation, including cardiovascular stimulation, increased gastric secretion, pituitary and adrenal stimulation, suppression of the immune system and wound healing, and possible contribution to delirium. Over the past few years, many studies have endeavored to objectively assess sleep in the ACUs, as well as the effect of mechanical ventilation and circadian rhythm changes critically ill patients. At this time, therefore, it is important to review published data regarding sleep in ACUs, in order to improve the knowledge and recognition of this problem by health care professionals. We have therefore reviewed the methods used to assess sleep in ACUs, factors that may affect sleep in the ACU environment, and the clinical implications of sleep disruption in the ACU.

Comorbid insomnia in sleep-related breathing disorders: an under-recognized association

BackgroundIn the clinical practice of sleep medicine, the coexistence of common sleep disorders is not uncommon. Patients with sleep disordered breathing (SDB) may present with insomnia, and studies have shown that SDB is common among insomnia patients. Little is known about the pathophysiological mechanisms underlying this coexistence, and limited information is available regarding the impact of each disorder on the other. It is essential to consider the effect of each disorder on the other and to understand the clinical consequences anticipated when treating each disorder in isolation. The management plan should be directed toward both disorders in a systematic and evidence-based approach. Unfortunately, a consensus standard approach for the management of comorbid insomnia and SDB is not yet available.MethodsTherefore, we have reviewed published studies that investigated insomnia in patients with different types of SBD; obstructive sleep apnea, central sleep apnea, and hypoventilation syndromes, as well as studies that assessed SBD in patients with insomnia. In addition, we reviewed the effects of SBD treatment modalities on insomnia and the effects of insomnia treatments on SBD.

Does Ramadan fasting affect sleep

Experimental fasting has been shown to alter the sleep‐wakefulness pattern in various species. As fasting during Ramadan is distinct from experimental fasting, the physiological and behavioural changes occurring during Ramadan fasting may differ from those occurring during experimental fasting. There has been increased interest in recent years in sleep changes and daytime sleepiness during Ramadan. Moreover, many of those who fast during Ramadan associate this fasting with increased daytime sleepiness and decreased performance. This raises the question of whether Ramadan fasting affects sleep. In this review, we discuss the findings of research conducted to assess changes in sleep pattern, chronobiology, circadian rhythms, daytime sleepiness and function and sleep architecture during the month of Ramadan. Where applicable, these findings are compared with those obtained during experimental fasting.

Behaviour and time‐course of sleep disordered breathing in patients with acute coronary syndromes

To our knowledge, no study has examined the persistence of sleep disordered breathing in acute coronary syndrome (ACS) patients. We examined the time course of SDB in ACS patients by assessing them within days of the acute event and again after 6 months.