Diabetes Pathophysiology
Sleep Disturbances and Glucose Homeostasis R Paulien Barf1
and Anton JW Scheurink2 1. PhD Student; 2. Professor of Neuroendocrinology, Department of Neuroendocrinology, Centre for Behaviour and Neurosciences, University of Groningen
Abstract
Sleep disturbances, induced by either lifestyle, shift work or sleeping disorders, have become more prevalent in our 24/7 Western society. Sleep disturbances are associated with impaired health including metabolic diseases such as obesity and type 2 diabetes. The question remains whether there is a direct effect of disturbed sleep on glucose homeostasis. Experimental studies under controlled laboratory conditions in both humans and experimental animals revealed that there are differences between the effects of acute or chronic sleep disturbance. Acute sleep restriction clearly leads to glucose intolerance, often combined with insulin resistance. Although glucose intolerance does also occur after chronic sleep disturbance, the changes in insulin can vary, dependent on the body weight changes in the various studies. The underlying mechanism that might cause the changes in glucose homeostasis after sleep disturbance remains unclear, but both the biological clock located in the nucleus suprachiasmaticus as well as orexinergic mechanisms in brain and periphery seem to be involved.
Keywords Sleep restriction, sleep deprivation, shift work, glucose homeostasis, hyperglycaemia, type 2 diabetes, rats, obstructive sleep apnoea
Disclosure: The authors have no conflicts of interest to declare. Received: 8 December 2010 Accepted: 21 February 2011 Citation: European Endocrinology, 2011;7(1):14–8 Correspondence: R Paulien Barf, Department of Neuroendocrinology, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands. E:
r.p.barf@
rug.nl
Over the past 50 years, average sleep duration in Western societies has decreased by two hours per night.1
Initially, this decrease in sleep
was observed mainly in adulthood, but recent epidemiological studies have shown a similar decrease in children and adolescents.2,3 A decrease in sleep includes not only the duration, but also the quality of sleep. Quality of sleep is generally defined in terms of changes in sleep architecture, the content of dreaming and the amount of awakenings.4
A decrease in length or quality of sleep has important consequences for an individual’s well-being. Sleeping problems are linked to many health and lifestyle problems, such as increased errors, loss of productivity, sleepiness during the day, impaired social activities and an elevated risk of accidents.5,6
Disturbed sleep has also been
identified as a risk factor for a variety of diseases, including psychiatric disorders such as depression7–9 dysfunctions.10–12
and immune system
These health problems are increasing as sleep loss and decreased sleep quality become more prevalent in our current 24/7 Western society.
Metabolic Consequences of Sleep Disturbances Sleep disturbances are also linked to metabolic dysfunctioning. Studies in shift workers provided the first (indirect) evidence for a relationship between sleep disturbances and impaired metabolism. Shift work has become more prevalent during the past decades and shows clear negative effects on sleep timing, length and quality.13 Shift workers are active during the night and sleep and eat at abnormal hours. They fall asleep in the morning, but are awakened ahead of time owing to their circadian rhythm, causing them to exhibit sleepiness and reduced performance.14
The shift work- 14
Another striking example of the relationship between disturbed sleep and increased risk for metabolic disorders derives from studies of patients with obstructive sleep apnoea (OSA). OSA is characterised by the recurrent collapse of the airway during sleep, which usually leads to arousals to resume breathing. The patients suffer from sleep fragmentation and hypoxemia, causing disturbed sleep architecture and an increased amount of awakenings.20,21
OSA
primarily changes the quality of sleep, whereas total sleep time is not dramatically altered. Vgontzas and colleagues22
were the first to
show that there is a relation between OSA and obesity, type 2 diabetes and cardiovascular disease. In fact, there is a bidirectional relationship: OSA leads to obesity, but obesity also directly affects OSA: weight gain or weight loss leads to a significant worsening or improvement, respectively, of sleep apnoea in adults.23,24
OSA is also
directly associated with insulin resistance and glucose intolerance, independent of changes in weight.25
© TOUCH BRIEFINGS 2011
induced changes, in particular sleep loss and disturbed circadian rhythmicity in eating and energy expenditure are associated with an increased susceptibility to develop obesity, type 2 diabetes and cardiovascular disorders.15,16
There is also a direct correlation between disturbed sleep and obesity, the main risk factor for developing cardiovascular diseases and type 2 diabetes. Evidence for this comes from several epidemiological studies, including those described by Caput and Van Cauter.17,18
In addition, the group of Gottlieb and co-workers19 provided evidence for a direct correlation between disturbed sleep and the increased prevalence of type 2 diabetes, independent of changes in body weight.
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