12: Sleep and the Circadian Rhythm
- Page ID
- 151267
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 12.1: Introduction
- This page emphasizes the critical role of sleep for overall health, highlighting that inadequate sleep can lead to serious issues like heart disease and depression. It notes that many adults, especially college students, often fail to achieve the recommended sleep duration. The page defines sleep biologically, illustrating that it involves reduced activity and varied brain wave patterns, indicating ongoing brain function.
- 12.2: Phases of sleep
- This page explains the phases of sleep, highlighting the differences between REM (Rapid Eye Movement) and NREM (Non-REM) sleep. It details the three NREM stages: NREM1 (light sleep), NREM2 (with K-complexes and sleep spindles), and NREM3 (deep sleep with delta waves). REM sleep features EEG activity akin to wakefulness. Sleep cycles through these stages approximately every 90 minutes, with varying intervals of REM and deep sleep throughout the night.
- 12.3: Why do we sleep?
- This page discusses the unclear purpose of sleep, presenting three theories: **Recuperation Theory**, which highlights sleep's role in recovery from wakefulness; **Evolutionary Adaptation Theory**, which suggests sleep patterns evolved for survival, though they create vulnerability; and **Brain Plasticity Theory**, which emphasizes sleep's importance in memory consolidation and learning through REM and NREM phases.
- 12.4: The circadian rhythm
- This page explores circadian rhythms, 24-hour cycles observed in living organisms, initiated by Jean-Jacque d’Ortous de Mairan's study of the Mimosa pudica plant in 1729. It details how these rhythms regulate physiological and behavioral aspects like sleep and hormone production, potential disruptions (e.g., jet lag), and the underlying genetic mechanisms.
- 12.5: Neurochemical signals
- This page explains the role of key neurotransmitters in sleep, highlighting adenosine, melatonin, and histamine. Adenosine signals sleepiness by accumulating with energy use, while caffeine opposes this. Melatonin, regulated by light, manages the sleep-wake cycle, with blue light inhibiting its production. Histamine promotes wakefulness and can induce drowsiness when antihistamines are used, though newer versions aim to mitigate this effect.
- 12.6: Brain structures involved in sleep
- This page explains how the hypothalamus and reticular formation control sleep and wakefulness. Key findings from Constantin von Economo's research indicate that the posterior hypothalamus is essential for wakefulness, whereas the anterior hypothalamus encourages sleep. It highlights neuron groups such as the suprachiasmatic nucleus and tuberomammillary nucleus that help regulate sleep-wake cycles.
- 12.7: Sleep disorders
- This page outlines various sleep disorders, including insomnia, sleep apnea, narcolepsy, restless legs syndrome, and periodic limb movement disorder (PLMD). Insomnia, affecting many, is linked to stress and often treated with behavioral changes. Fatal familial insomnia is a rare hereditary condition leading to death. Sleep apnea disrupts breathing and causes daytime drowsiness. Narcolepsy results in uncontrollable daytime sleep attacks.