What does an increase in theta waves often signify in an EEG?

An increase in theta waves in an EEG is often associated with light sleep or deep relaxation. Theta waves typically have a frequency range of 4 to 8 Hz and are commonly observed during states of drowsiness, meditation, or even daydreaming. In particular, they are prevalent in the transition phase between wakefulness and sleep, representing a state of reduced alertness and brain activity compared to the beta waves that characterize active alertness.

This pattern indicates that the brain is moving into a more restful and relaxed state, as seen during light sleep when one may still be somewhat aware of external stimuli but is primarily engaged in the processes of sleep initiation and relaxation. Therefore, when theta waves are prominent, it signals a shift away from higher cognitive engagement and towards a more tranquil and restorative brain state.