Getting a soft tingling sensation on your forehead is maybe the most common experience. It will feel like something is tickling your forehead, like a hair or small insect, and you will notice how you repeatedly try to brush something off your forehead. You may also feel a tingling sensation on your crown chakra at the top of your head.
Many people get headaches from activating their third eye. This headache may last for a couple of days, and you just need to rest your head for some time until it passes.
Intense Pressure on Head
You may also experience a very intense pressure on your entire head, whenever you are meditating, like a huge person is squashing your head with his hands. This can be so intense that it feels like your scull is about to crush. When you stop the meditation the pressure goes away immediately.
Many people experience having more nightmares or extremely vivid dreams. This may be caused by your activation of your pineal gland, which produces the natural psychedelic drug DMT (Dimethyltryptamin), which is present during sleep. But activating your pineal gland can increase the production of DMT in the brain.
Seeing Lights and Objects
You may experience seeing lights or objects in your minds eye, as you meditate. These lights are often bright colored beams or spirals of vibrant light. Some people begin to see religious objects while meditating, but most people see an eye or the outline of an eye.
Hearing a Loud Popping Sound
Some people hear a very loud popping sound or crackling sound inside their brain. This is said to be the activation of the pineal gland, which is located in the middle of the brain. This can be a quite overwhelming and shocking experience to some, as the sound can be very loud.
Opening and activating your third eye can increase your awareness and focus. You may notice how you begin to pay attention to more details and that your eyes constantly catch even the tiniest movement in your peripheral vision. Sometimes even when nothing is there... at least nothing physical.
These were some of the symptoms and side effects you may experience from opening and activating your third eye and pineal gland.