The link between sleep deprivation and chronic disease
Key Takeaways
As a physician, chances are that you’ve experienced your fair share of sleepless nights. But, sleep is a cardinal aspect of health, with humans needing to spend one-third of their life in slumber to remain healthy.
Chronic disease has taken on a greater role in premature death and illness. Researchers have increasingly focused on the role that sleep plays in such disease, with insufficient rest linked to diabetes, heart disease, obesity, and depression, according to the CDC.
Let’s take a closer look at the relationship between these chronic conditions and insufficient sleep.
Diabetes
Various mechanisms underlie the progression of sleep disorders to insulin resistance and beta-cell dysfunction, including sleep fragmentation, activation of the sympathetic nervous system, and hypoxia, according to the authors of a review published in Healthcare.
Sleep fragmentation results in an increase in sympathetic activity and inflammation, as well as obesity. During sleep, the parasympathetic nervous system is in control, thus slowing heart rate, blood pressure, respiration rate, gut motility, and basal metabolism, as well as lowering body temperature. If the parasympathetic relinquishes control to the sympathetic nervous system, there is a higher load on the circulatory system, higher basal metabolism, and higher levels of stress hormones, plus a higher risk of developing insulin resistance or diabetes.
Intermittent hypoxia present during sleep apnea can also result in insulin resistance. Periods of low-oxygen perfusion followed by compensatory high-oxygen perfusion perturbs normal metabolism and yields reactive oxygen species. This reactive oxygen damages cells and results in the inflammation of adipose tissues and insulin resistance.
Reversing the diabetes-promoting impact of sleep deprivation may be as simple as prescribing sleep to patients, the review authors wrote. Another concern should be sleep hygiene. “The importance of sleep prescription and sleep hygiene has not been fully realized in diabetes prevention,” they added.
With regard to sleep apnea, studies have indicated that treating obstructive sleep apnea with continuous positive airway pressure (CPAP) can decrease levels of insulin resistance and improve the control of blood sugars in those with prediabetes or type 2 diabetes.
Obesity
Laboratory research has demonstrated that decreased sleep duration leads to metabolic changes that are linked to obesity, with epidemiologic studies also linking decreased sleep times with increased body weight. The CDC noted that although this association is present in all groups, it is most detrimental in childhood/adolescence because a lack of sleep in kids interferes with the function of the hypothalamus, which regulates appetite and energy expenditure.
According to the Sleep Foundation, the negative impact of sleep on obesity levels can be mediated through various sleep-hygiene interventions including:
Exercise, especially in natural light to promote a healthy sleep-wake cycle
Choosing the right mattress that properly aligns the spine and balances contact pressure between the body and the mattress
Selecting foods carefully, including the limitation of carbohydrate intake, and avoiding foods up to an hour before bedtime
Depression
Melancholia and sleep disturbances have been recognized as coexistent for eons. Polysomnography results indicate disturbances in sleep continuity in those with depression, thus revealing decreases in slow-wave sleep and disinhibition of REM sleep, with a decrease in REM latency, an increase in REM density, and an increase in total REM sleep time.
Some experts anticipated that REM abnormalities could predict subtypes of depression, although such relationships were never elucidated, according to the authors of a review published in Neuropsychopharmacology. Nearly all antidepressants thwart REM sleep, with a time-dose relationship evident.
Subjective complaints about sleep disorders entail difficulties falling asleep, difficulties maintaining sleep, waking up too early, and feeling daytime fatigue/sleepiness. A nonpharmacologic first-line treatment option for comorbid sleep disorders in those with depression includes cognitive-behavioral therapy. On the other hand, benzodiazepines are panaceas that work only 3 to 4 weeks. Sedating antidepressants (eg, amitriptyline, doxepin, trimipramine, trazodone) and atypical antipsychotics (quetiapine, olanzapine) are other options to induce sleep in those with mental illness, such as bipolar disorder, major depression, or schizophrenia.
Chronotherapy, or treatment that takes into account the body’s natural cycles/circadian rhythms, is emerging as a viable therapy in those with mental illness and sleep disorders. As described by the review authors: “Behavioral chronotherapeutic approaches encompass bright light therapy, dark therapy, dawn simulation, sleep-wake manipulations (sleep deprivation, sleep phase advance/delay), often in combination with precisely personalized timed low-dose fast-release melatonin agents, as well as social rhythm therapy.”
The authors of the review noted that oftentimes mental health professionals erroneously view insomnia and symptoms of circadian dysfunction as symptoms of a mental disorder that will remit when the mental disorder is treated or when some other “wrong” drugs are administered.
“A main reason for this is that there is a serious lack in the knowledge about basic sleep and chronomedicine across fields in the medical professions, maybe because these disturbances are transdiagnostic,” wrote the authors. “[T]here still is a strong need for further education of health professionals, in particular in psychiatry (hospital and community doctors, nurses, health advisors), in the domain of sleep and chronomedicine to enable them to recognize, properly diagnose and treat individuals with sleep problems."
They added: "Specific evidence-based treatment strategies incorporating chronomedicine (right drug, right dose, right time) for these disorders are available and might offer not only to improve the underlying sleep/circadian disorder but concomitantly ameliorate the outcome and course of mental disorders compared to standard psychiatric treatment.”
Heart disease
The American Heart Association singles out sleep duration and poor sleep quality as major contributors to heart disease, with risks including high blood pressure, elevated cholesterol, and atherosclerosis. Habitual short sleep increases the chance of cardiovascular events.
Here are some other points noted by the AHA:
A modest link exists between short and long sleep duration (ie, 9 or more hours) and stroke, as well as death.
Those with common sleeping disorders, such as obstructive sleep apnea or insomnia, are at greater risk for heart arrhythmias, plaque buildup, coronary artery disease, and heart failure.
Neurological sleep disorders such as restless leg syndrome, which occurs in 7%-10% of Americans, can predict heart disease.
People with Type 1 narcolepsy don’t experience normal blood pressure dips during sleep, which could raise the risk for heart disease, although more research is needed.
Bottom line
Lack of sleep or poor sleep quality is tied to a plethora of pathology. If your patients (or you) are struggling with sleep, one piece of general advice promoted by both the CDC and the AHA is going to bed and waking at the same time every day (including weekends). Other tips include sleeping in a dark, quiet place set to a comfortable temperature; banning electronic devices from the bedroom; eschewing alcohol, caffeine, and big meals before sleep; and exercising.
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