Summary
Highlights
Amber O'Hearn shares her long-standing interest in sleep, stemming from discovering that sleep restriction could treat depression. She then shifted focus to ketogenic diets, which resolved her depression. The presentation will explore basic sleep physiology and how it integrates with ketogenic metabolism, focusing on metabolic and neurological impacts.
Sleep is essential and homeostatically regulated. Sleep metrics include duration, efficiency (proportion of time asleep, number of awakenings), and daytime sleepiness, measured subjectively or through objective tests like the Multiple Sleep Latency Test. Sleep stages, primarily REM and non-REM, and circadian rhythms also provide measurable characteristics for evaluating sleep.
Sleep is distinguished behaviorally (stillness, specific posture, lack of responsivity) and through electroencephalogram (EEG) brainwave patterns. REM sleep resembles wakefulness in brain activity but with muscle paralysis. Non-REM sleep includes light and deep sleep; deep sleep (slow-wave sleep or SWS) is characterized by slow delta waves and coordinated neuronal silencing. Most deep sleep occurs early in the night, while REM sleep increases in the latter half.
SWS is linked to metabolic and endocrine functions, such as its correlation with BMI and its role in glucose tolerance and insulin resistance. It's crucial for cognitive function, memory consolidation, and is often reduced in neurodegenerative conditions like Parkinson's and Alzheimer's. Increased brain energy use, particularly during waking, leads to more SWS during subsequent sleep.
Circadian rhythms are biological patterns adapting to light-dark cycles, optimizing physiological processes like digestion and immune response. Cortisol release, for example, is circadian, peaking after waking. Growth hormone release, however, is sleep-dependent rather than strictly circadian, peaking with SWS. Circadian misalignment, caused by irregular sleep or eating, can impair glucose and insulin responses, affecting metabolic health.
Limited research exists directly on ketogenic diets and sleep. Fasting studies provide insights, as ketogenic diets share metabolic similarities with the 'fat-adapted' phase of fasting. During fasting, the body transitions from glucose to fat metabolism, using ketone bodies for brain energy, and various mechanisms spare lean mass. Studies show fasting increases SWS and decreases REM sleep, especially in species with significant fat reserves.
Injections of acetoacetate (a ketone body) and BDNF into the brain increase SWS and reduce REM, similar to fasting and ketogenic effects. While some studies suggest ketogenic diets increase REM in individuals with deficits, this appears to be a restoration to normal levels. Ketogenic diets robustly increase SWS, potentially by increasing brain energy use, and are associated with improved cognitive function.
Orexin stabilizes wakefulness and increases appetite; its levels rise during fasting/low glucose states, which might explain improvements in narcolepsy symptoms on ketogenic diets. Adenosine, a product of ATP breakdown, builds up during wakefulness, promoting SWS and inhibiting neural activity. Ketogenic diets increase both orexin and adenosine, which have opposing effects on wakefulness. NAD+, a coenzyme elevated by ketogenic diets, can restore circadian gene expression, suggesting a positive impact on circadian alignment.
Ketogenic diets and a healthy sleep profile share similar positive effects on metabolism and cognition. Ketogenic diets appear to improve sleep parameters, particularly increasing SWS. It's hypothesized that these sleep effects may be part of the mechanism by which ketogenic diets exert therapeutic benefits, such as mood stability and cognitive function rescue. Further research is needed to determine if enhanced SWS directly correlates with better therapeutic outcomes.
Sleep disturbances are a common but often neglected aspect of health. Many medical conditions, such as inflammatory bowel disease, can cause sleep issues that are resolved only by addressing the root cause. It's important to investigate underlying medical conditions rather than attributing sleep problems solely to sleep hygiene or, for women, to menopause, as symptoms like night sweats can be misattributed.
The 'Dawn phenomenon' involves higher morning blood sugars due to hormonal releases (growth hormone, cortisol) that stimulate gluconeogenesis. Sleep deprivation exacerbates insulin resistance, making it harder for insulin to control glucose levels. This highlights how sleep quality directly impacts metabolic health and blood sugar regulation, especially in individuals with borderline insulin resistance.