Delta brainwaves are the slowest, lowest frequencies (.5 Hz to 3 Hz) of the five different types of brainwaves: gamma, beta, alpha, theta and delta (listed from highest to lowest frequency). Delta waves are prominent during dreamless sleep and the deepest stages of meditation. They are also central to unconscious bodily functions such as digestion and heartbeat.

All five brainwaves are essentially present in the brain, even in trace amounts, at all times; however, depending on one’s current state of mind, one type will be particularly dominant.  Brainwaves can be observed with an electroencephalograph (EEG), a tool which records electrical activity in the brain through electrodes built into a cap. If any of the five brainwaves are overactive or underactive, problems can occur in cognition and/or mental health.

When delta waves are functioning optimally, we obtain restful sleep, have a boosted immune system and increased empathy. Delta brainwaves are believed to stimulate healing and regeneration, which is why restorative sleep is so important for the healing process. Delta  waves are most prominent in infants and very young children. As we get older, however, we produce less delta, even during deep sleep.

When people have too little delta activity, sleep will be more restless and they will be unable to feel refreshed and rejuvenated upon waking. Too much delta activity could lead to severe attention deficit hyperactivity disorder (ADHD) and learning problems. Traumatic brain injury (TBI) may also lead to an overflow of delta brainwaves, in which the person will have trouble staying awake.

Example: The patient had an abundance of delta brainwaves after experiencing traumatic brain injury from the car accident. She was in a coma for three days.