All brainwave frequencies are useful and beneficial at certain times – there is no brainwave that is intrinsically better than another. However, by deliberately choosing to attain a particular brainwave state, a corresponding mental state can be brought about at the same time. For example, a working person who has been in an overly alert beta brainwave pattern for many hours can quickly shift their mind and body into a relaxed state by listening to a few minutes of brainwave entrainment music for inducing alpha or theta brainwaves.

The final suggestion I have to offer is that you make your practice a regular, consistent habit. You don’t have to be perfect but you do need consistency. Like any other skill, entering meditation will develop in direct proportion to the consistency of your practice. Missing a session occasionally is not going to derail all your progress. But frequently skipping or blowing insincerely through practice is not going to produce any noteworthy results. There isn’t any hard and fast rule from frequency of practice that always applies to everyone, but most of us will instinctively know whether or not we’re giving our practice the time and effort it requires.
Progressive muscle relaxation is a two-step process in which you systematically tense and relax different muscle groups in the body. With regular practice, it gives you an intimate familiarity with what tension €”as well as complete relaxation €”feels like in different parts of the body. This can help you react to the first signs of the muscular tension that accompanies stress. And as your body relaxes, so will your mind.
If you can't spend a full hour in meditation, try the 30 minute Theta Standalone Meditation. This track takes you a little deeper into exploring the Theta frequency than the first Theta track, so it can also be a progression if you have used the first Alpha/Theta combination. If you do have a full hour for Theta, use the 60 minute Theta Standalone meditation.
Another consideration of stress is whether it is acute or chronic. “Acute stress” is what an individual experiences at the time the stressor is encountered (4). The stress response is activated, and the body returns to homeostasis once the challenge of the stressor is removed or the person successfully manages the situation. For example, an individual on the way to an important meeting gets into a traffic jam and realizes she is going to be late; the stress response starts. When she calls her boss and learns that she can conference into the meeting while on the road, the stress response subsides with the resolution of the situation. When an individual experiences acute stress on a consistent basis, such as with overcommitting at work or constant worrying, it is referred to as “acute episodic stress” (4). Individuals who experience acute episodic stress often show signs and symptoms of stress (Table 1) that can negatively impact physical and psychological health. These individuals can learn how to change behaviors and manage their stress to prevent these consequences.
The binaural-beat appears to be associated with an electroencephalographic (EEG) frequency-following response in the brain (3). Many studies have demonstrated the presence of a frequency-following response to auditory stimuli, recorded at the vertex of the human brain (top of the head). This EEG activity was termed "frequency-following response" because its period corresponds to the fundamental frequency of the stimulus (Smith, Marsh, & Brown, 1975). Binaural-beat stimulation appears to encourage access to altered states of consciousness.
But the question is: Does it have a special effect on the brain? A lot of people think so. The basic claim being made for binaural beats is "resonant entrainment". Entrainment, in physics, is when two systems which oscillate at different frequencies independently are brought together, they synchronize with one another, at whatever the combined system's resonant frequency is. Examples of entrainment occur in animals in nature; for example the chirping of crickets or the croaking of frogs. Synchronization of menstrual cycles in women is another example. Even people coming together and dancing with one another is a type of entrainment. The basic claim for binaural beats is that the perceived low-frequency beat will entrain your brain wave pattern, thus forcing your brain into some desired state.

^ Trost W. and Vuilleumier P., Rhythmic entrainment as a mechanism for emotion induction by music: a neurophysiological perspective. In The Emotional Power of Music: Multidisciplinary Perspectives on Musical Arousal, Expression, and Social Control, Cochrane T., Fantini B., and Scherer K. R., (Eds.), Oxford, UK: Oxford University Press; 2013, pp213–225.

Beta waves are the most common and most prevalent in the brain. These are the brain waves of alertness, dominating your normal waking state of consciousness. The Beta state relates to “fast” activity with neurons firing abundantly, in rapid succession, with attention focused directly towards cognitive tasks and the outside world. Beta activity is engaged in focused mental activity, problem solving, judgment and decision making. New ideas and solutions to problems flash like lightning into your mind.

I have many new age, meditation, classical and jazz cds that I use for relaxation. This Steven Halpern cd is now my favorite one. I can listen to it for hours on end while I read, write, use the computer, or just veg out on the couch at home or lounge at the pool. I especially love the tracks with the ocean wave sounds mixed in with the electronic music. I definitely am in the theta brain wave state while listening to it, and I know that's the reason it is so much more soothing than any other cd that I own. It is really great for eliminating any anger or anxiety that I may be feeling. I believe it's also improving my sleep. I give this cd the highest possible recommendation!

Brainwave Entrainment is an assisted form of meditation using pulses of sound. Entrainment is a process of synchronizing two different beats to become harmonious. Brainwave entrainment works by pulsing a different sound in each ear to stimulate the brain into altered states of consciousness. Examples including Binaural Beats and Isochronic Tones, which are best experienced with headphones to assist with relaxation, deep sleep and focus.

Brainwave entrainment is a colloquialism for such 'neural entrainment', which is a term used to denote the way in which the aggregate frequency of oscillations produced by the synchronous electrical activity in ensembles of cortical neurons can adjust to synchronize with the periodic vibration of an external stimuli, such as a sustained acoustic frequency perceived as pitch, a regularly repeating pattern of intermittent sounds, perceived as rhythm, or of a regularly rhythmically intermittent flashing light.