Chapter 2: States of Consciousness
A cup of coffee at 9 a.m. and a glass of wine at 9 p.m. both alter your consciousness. So do falling asleep, meditating, daydreaming, and being knocked out by general anesthesia. “Consciousness” is a spectrum, not a switch, and this chapter is about what changes along that spectrum.
There are two main drivers of altered consciousness: your brain on its own (sleep, dreaming, meditation) and your brain on chemicals (coffee, alcohol, opiates, hallucinogens). Both routes converge on the same underlying circuits, which is why sedatives can mimic sleep and why stimulants can mimic a panic attack.
The Brain Wave Vocabulary Runs Through Everything
Before we even get to sleep, a quick note about brain waves, because they show up in every section of this chapter.
Electroencephalogram (EEG) electrodes on the scalp record rhythmic voltages reflecting the synchronized firing of millions of cortical neurons. The frequencies cluster into four bands:
- Beta (12–30 Hz) - alert, focused wakefulness. Fast, low amplitude.
- Alpha (8–13 Hz) - relaxed wakefulness, eyes closed, daydreaming, light meditation.
- Theta (4–7 Hz) - drowsiness and light sleep (stage N1).
- Delta (0.5–2 Hz) - deep sleep (stage N3). Slow, high amplitude.
Roughly, faster = more alert. Know this before you hit the sleep stage section.
In This Chapter
- 2.1 Sleep Stages, Brain Waves, and Circadian Rhythms
- 2.2 Dreams and Dream Theories
- 2.3 Sleep Disorders, Hypnosis, and Meditation
- 2.4 Psychoactive Drugs: Depressants, Stimulants, Hallucinogens, Opiates
- 2.5 Reward Pathway, Tolerance, and Withdrawal
- Section Test
What You Will Walk Away With
By the end of this chapter you should be able to:
- Describe each sleep stage by brain wave and biological function.
- Explain circadian rhythms and how melatonin and light control them.
- Name the two major theories of dreaming and which phenomena each one explains best.
- Distinguish insomnia, narcolepsy, sleep apnea, and the parasomnias that show up in N3.
- Classify any psychoactive drug into depressant, stimulant, hallucinogen, or opiate, and name the receptor or neurotransmitter each one acts on.
- Draw the VTA → nucleus accumbens dopamine pathway and explain how it underpins addiction.
- Distinguish tolerance, dependence, withdrawal, and substance use disorder.
Ready? Start with sleep stages - they anchor everything else in the chapter.