Acute effects of night work and meals on blood glucose levels

Circadian desynchrony and glucose metabolism

The circadian timing system controls glucose metabolism in a time-of-day dependent manner. In mammals, the circadian timing system consists of the main central clock in the bilateral suprachiasmatic nucleus (SCN) of the anterior hypothalamus and subordinate clocks in peripheral tissues. The oscillations produced by these different clocks with a period of approximately 24-h are generated by the transcriptional-translational feedback loops of a set of core clock genes. Glucose homeostasis is one of the daily rhythms controlled by this circadian timing system. The central pacemaker in the SCN controls glucose homeostasis through its neural projections to hypothalamic hubs that are in control of feeding behavior and energy metabolism. Using hormones such as adrenal glucocorticoids and melatonin and the autonomic nervous system, the SCN modulates critical processes such as glucose production and insulin sensitivity. Peripheral clocks in tissues, such as the liver, muscle, and adipose tissue serve to enhance and sustain these SCN signals. In the optimal situation all these clocks are synchronized and aligned with behavior and the environmental light/dark cycle. A negative impact on glucose metabolism becomes apparent when the internal timing system becomes disturbed, also known as circadian desynchrony or circadian misalignment. Circadian desynchrony may occur at several levels, as the mistiming of light exposure or sleep will especially affect the central clock, whereas mistiming of food intake or physical activity will especially involve the peripheral clocks. In this review, we will summarize the literature investigating the impact of circadian desynchrony on glucose metabolism and how it may result in the development of insulin resistance. In addition, we will discuss potential strategies aimed at reinstating circadian synchrony to improve insulin sensitivity and contribute to the prevention of type 2 diabetes.

The Effect of Night Duty of Pharmacists on Sleepiness and Concentration at Daytime

Background: The changing responsibilities of pharmacists contribute to a lack of qualified pharmacists to fill vacant positions, particularly in rural areas. Consequently, pharmacy managers cover various duties, including an increasing number of nights being on duty that can impair daytime concentration and performance. The objective of the study was to assess the effect of night duties on daytime sleepiness, sleep quality, and concentration abilities of pharmacists. Methods: 22 pharmacists, both sexes, aged 27 to 60 years, were recruited and their sleep time, sleep efficiency, and mobility (actigraphy) were assessed during a night on duty and a control night using an actimetry. Daytime sleepiness and concentration were assessed using standardized questionnaires (ESS, KSS, d2-R). Results: Significant differences were observed between the night shift and control nights with respect to sleep time, sleep efficiency, and mobility. Daytime sleepiness was significantly increased after night shifts (ESS: 11.64 vs. 2.09; KSS: 6.77 vs. 2.41 after a night shift and control night, respectively; p < 0.001) and concentration diminished compared to control nights (d2-R KL: 220.95 vs. 260.36 after a night shift and control night, respectively; p < 0.001). Conclusions: The results provide evidence that night duties lead to high daytime sleepiness in pharmacists, which in turn may negatively affect their ability to concentrate and their error rate. Existing regulations on emergency pharmacy services should be reconsidered regarding the safety of the pharmaceutical supply.