Sleep Deprivation, the Blood-Brain Barrier, and Neuroinflammation
So many of us struggle with sleep, and have difficulties getting enough rest in terms of both time and quality. Whether it be due to nighttime awakenings to care for children or loved ones, a demanding job, or a health condition, sleep problems can cause trouble in many different aspects of our health. We often hear that sleep is healing and restorative, and know this intuitively, but what is the research that supports this?
It turns out that sleep deprivation affects far more than energy levels, contributing to inflammation, impaired immune function, metabolic dysfunction, and even changes to the blood-brain barrier. Neuroinflammation is increasingly recognized as a contributing factor in conditions such as Alzheimer's disease, depression, and cognitive decline, making factors that affect blood-brain barrier integrity an important area of research (and for our personal health maintenance as well!).
Sleep Deprivation and Physical and Emotional Well-Being
One way we can learn about the benefits we derive from sleep is from sleep deprivation studies. Sleep deprivation has been shown to be associated with worse performance on cognitive tasks and motor performance, depression, feelings of burnout, decrease in feelings of empathy, increased vulnerability to infection, weight gain, and decreased ability to manage increases blood glucose.
Moderate sleep deprivation impairs mental and physical performance to a degree comparable to a blood alcohol concentration above the legal driving limit.
In fact, moderate sleep deprivation has been shown to impair both mental and physical performance as much as a blood alcohol content of 0.1%, which in most locations exceeds the legal limit. These findings of course become issues of significant concern in jobs where sleep deprivation is common such as medical residents, emergency room physicians, and military personnel. Although we don’t all fit into these categories, that does not alleviate the importance that healthy sleep has for us all.
The Pro-Inflammatory Effects of Diminished Sleep
Many inflammatory markers and hormones are impacted by sleep and the lack thereof. Many of these hormones, which many are familiar with like cortisol and melatonin, normally fluctuate throughout the day, and the impact of sleep loss is not surprising. Additional hormones that regulate our body’s function, such as growth hormone, leptin, and ghrelin, also have a circadian variation and thus, alterations in our sleep cycle can impact them. The night-time decreases in the stress hormone cortisol and increases in the sleep-supportive antioxidant melatonin are well known to be important for quality sleep. Immune and inflammatory mediators such as interleukin (IL)-6 also normally increase at night and play a role in inducing fatigue.
The inflammatory effects of sleep deprivation can persist after several nights of recovery sleep.
Markers of inflammation such as C-reactive protein (CRP), which typically do not vary throughout the day in healthy subjects, have been shown to be increased with both acute and short-term sleep deprivation. Even more surprisingly, the increases in CRP extend beyond the days with diminished sleep. Levels of CRP and other proinflammatory cytokines have been shown to continue to be high with two days of sleep recovery (8 hours/night) after the period of sleep restriction. In another study, acute sleep deprivation (from only 34 hours) was shown to increase levels of the pro-inflammatory cytokine TNF-α. The circadian rhythm of the cytokines IL-6 and TNF-α has been observed to be shifted in individuals with chronic insomnia, a factor which may be important to consider with interventions directed at inflammation in addition to other supportive therapies.
The Blood-Brain Barrier, Sleep, and Stress
If these factors alone are not alarming enough to cause us to retreat back to bed for an extra hour of sleep, this one may be. The integrity of the blood-brain barrier, which is crucial for protection of the central nervous system from circulatory proteins and toxins that may contribute to neuroinflammation and damage, also is adversely affected by sleep restriction. The low-grade inflammation associated with sleep loss and the previously mentioned increases in inflammatory markers may lead to the altered function of the brain cells and tight junction proteins, weakening the blood-brain barrier.
Disruption of the tight junctions of the blood-brain barrier may contribute to development or worsening of numerous neurodegenerative diseases including Alzheimer’s disease, amyotrophic lateral sclerosis, multiple sclerosis, and more. Stress also increases permeability of the blood-brain barrier via mast cell activation through corticotropin-releasing hormone (CRH), a hormone produced by the body when it senses acute stress. Elevations in CRH and cortisol, a stress hormone CRH stimulates, are also associated with disrupted sleep, perpetuating the trouble.
Can Naps Reduce the Effects of Sleep Deprivation?
Although the reports from patients and self-assessment on the benefits of napping may be quite varied, positive effects generally have been shown. A meta-analysis and systemic review surveying the impact of a scheduled nap in populations such as emergency medical services personnel and similar shift workers found that a nap had moderate yet significant positive effects on sleepiness both during and at the end of a shift. In placebo-controlled settings, a nap has been shown to have beneficial effects on sleep-deprivation symptoms as well as biochemical parameters after a night of total sleep loss. After taking a two-hour nap, subjects experienced significantly less sleepiness, with trends towards improvements in psychomotor vigilance tasks (tasks like pressing a button every time a light flashes). Biochemically, the two-hour nap was found to reverse the changes to cortisol and the inflammatory cytokine IL-6 caused by one night of sleep loss as well.
Sleep Is More Than Rest: Why Sleep Matters for Overall Health
Regardless of status of health or disease, the research shows that the physiological changes experienced with a loss of sleep, especially on a prolonged basis, can have significant impact, shedding light on the importance of sleep for far more than just alertness and energy levels. Research demonstrates that healthy sleep supports immune function, regulates inflammation, protects the brain, and promotes metabolic health. While occasional sleep loss is inevitable, chronic sleep deprivation may have consequences that extend well beyond feeling tired the next day. Prioritizing sleep remains one of the simplest and most effective tools for supporting long-term health and resilience.
Written by Dr. Carrie Decker, ND
Sleep Deprivation and Inflammation: Frequently Asked Questions
-
Sleep deprivation increases inflammatory markers such as CRP, IL-6, IL-17, and TNF-α, which may contribute to chronic disease.
-
Yes. Research has shown sleep deprivation is associated with increased vulnerability to infection and impaired immune function.
-
Sleep restriction may increase inflammation, alter blood-brain barrier function, and negatively affect cognitive performance.
-
Studies suggest naps may improve alertness and partially reverse some inflammatory and hormonal changes caused by sleep deprivation.