A few years ago, I was introduced to this curious little device called the Muse: a brain sensing headband that guides its wearer through meditation by gently informing them when they get distracted.
It looks pretty wonky and futuristic.
At the time, I didn’t have a meditation practice, so I didn’t try it for its intended purpose. But I was curious about how the Muse was able to “measure brain signals much like a heart rate monitor senses your heartbeat.”
That’s when I was introduced to the concept of electroencephalography (EEG) neurofeedback. Our brains are constantly emitting electrical signals due to activity from single or multiple interacting neurons. EEG is a method for measuring the large-scale oscillations in these signals. The measured results are categorized by their wave properties: frequency, amplitude, and phase.
By analyzing the waveforms, we can get fascinating insights about some of our cognitive functions, like memory and motor control. The Muse works by tracking our EEG signals and analyzing them in real time.
EEG on humans was studied as early as 1924, mainly for researchers to understand seizures. In the past decade, there’s been renewed interest in EEG research. This is partially because people are becoming more curious about hacking into their own cognitive abilities.
Four Types of EEG Waveforms
In clinical situations, EEG feedback is generally divided into four types: alpha, beta, theta, and delta. Each type describes a different range of frequencies in electrical activity given off by our neurons.
- Beta: over 14 Hz
- Alpha: between 8 and 14 Hz (wave cycles per second)
- Theta: between 4 and 8 Hz
- Delta: less than 4 Hz
Studies in the last two decades have been able to distinguish when each type of EEG wave arises. They’ve also been able to induce desirable changes in both healthy people and in patients with neurocognitive conditions, such as dementia, by altering their EEG patterns.
Beta waves are emitted when we’re awake and cognitively alert. When you’re solving an algebra problem, thinking strategically, or focused on a task, you’re typically in beta. Beta waves are also exhibited over a range of emotional states, including anything from an active calm state to a stressed and anxious state.
Alpha waves are what we emit when we’re relaxed or reflecting while awake. When you’re daydreaming, taking a mental break, or chilling by a pool, you’re likely exhibiting alpha waves. When you’re contemplating existence abstractly while going for a walk, you’re also likely in alpha.
Theta waves are typically associated with drowsiness, meditation, or light sleep in adults. But they also appear when you’re doing a fairly mindless, repetitive task, such as taking a shower, driving on an empty freeway, or going for a long run.
Fascinatingly, theta plays a role in learning, memory, and attentive effort. In healthy adults, it arises with the following experiences:
- Prolonged concentration: concentration is known to be associated with beta waves, but prolonged concentration induces theta waves.
- Flow state: Theta activities in the frontal brain areas increased with self-reported flow states in a 2018 study from Frontiers in Psychology. The flow state occurs when you’re so immersed in an activity that you don’t actively notice time and space anymore.
- Meditation: “no-thought” meditation has been observed to increase theta waves. This type of meditation involves the meditator being fully aware and awake, but not experiencing any unwanted thoughts.
- Recognition memory: the ability to recognize previously encountered objects, people, and events. Theta is associated with both memory formation and recognition.
- Working memory load: when performing a working memory task, such as remembering a series of numbers in a few seconds-span, theta activity was observed to increase during both the retention period and the recall period.
- Right before falling asleep, or hypnagogia: when you’re about to fall asleep, your inhibitions are low and your thoughts flow quickly. By directing, and recording these thoughts, you’re able to access your mind at its most creative. (Famous folks have used techniques to wake themselves as they dose off to do this, including Albert Einstein and Salvador Dali.)
- Right after waking up: as above. This is why so many productivity hacks involve the first hour after waking.
Delta waves are high-amplitude, low-frequency waves that occur during deep sleep in adults, babies, and children. They do not normally occur during waking hours. During delta wave sleep, neuron activity is significantly reduced.
Mixed states and conclusion
EEG waves are emitted by different parts of the brain. When measured, researchers often distinguish between wave activity in the frontal, central, and posterior parts of the brain. This means that wave types are often found in conjunction. For example, theta waves and alpha waves frequently occur together: in hypnagogia, for one, and in the flow state.
I’ve found it helpful to have some understanding of the different EEG states. It’s helped me understand when I should tackle certain tasks over others, and when I should attempt to induce certain states over others. I’ll frequently allow myself to slip into alpha or theta at times to access my creative mind.
There are a ton of resources out there for people to put themselves in certain states – theta and delta are popular ones. Let me know if you explore them, and what the results are!
- This paper, EEG-neurofeedback for optimising performance. I: a review of cognitive and affective outcome in healthy participants.
- Jensen, O. and Tesche, C. Frontal theta activity in humans increases with memory load in a working memory task. Found here.
- Medscape article on Normal EEG Waveforms.
- What is the function of the various brainwaves? From Scientific American.