An authentic spiritual awakening marks the beginning of a journey to understand who you are - genuinely realizing and being THAT true nature (whatever we want to call it as - emptiness, nothingness, awareness, consciousness, unconditional acceptance, connection with life). Without a conscious glimpse of this, we can go through the never-ending spiral of life - trying to achieve, trying to be successful, fulfilling desires, wanting in a never ending quest for fulfillment, freedom and happiness.
Spiritual awakenings are like tornadoes; they can blow up everything within you spontaneously and reveal to you what you are. This shift is not easy for the mind and body initially. There is no way one can plan these awakenings; they come at a time utterly uncalled for. But in retrospect, you grasp that the grace of awakening happened at the accurate moment needed and the soul that wanted freedom had a glimpse through an awakening. But chances are it won't stay that way, and we slip back to ego. From here, the right path has to be chosen and the right teacher. There are lot of teachings that can make you feel better, heal better, provide security, train you to replace your beliefs, and achieve better (these all are in the healthy ego land, but still an ego and these have their own place, but not in the realization of your true nature and authentic awakening). Realizing your true nature and spiritual freedom has got nothing to do with being happy, feeling secure, or achieving; in fact, any attempt to always feel better and be better will take you in the opposite direction.
In an authentic awakening, there is an unshakeable drive and quest to know the truth (I can't stress this enough!). And this will take you to those teachers and teachings with whom you feel connected. Something within you can sense the authentic teachings and teachers, our egos may reject it, but you will be drawn to those teachings.
Let's explore the symptoms and signals of a spiritual awakening. Although I have organized them into stages, we can move back and forth and all over the place. In general, this is what I have observed in retrospect:
First Stage of Awakening
You crave meaning and purpose
Have anxiety and an existential fear
You see how you and most people are unhappy.
You realize how everyone around you is looking for happiness and joy through fame, money, and recognition; you can start and feel the desperate attention people want
You intuitively understand achievement, success, and recognition are not the path to happiness (Yay! this is a huge step)
You want to go beyond the usual "personal" development and "healing to achieve" self-help techniques.
You feel connected to spiritual teachings. You also notice and observe how some teachers use healing and the law of attraction/manifestation technique to satisfy their ego desires and eventually turning into spiritual narcissists, and you move away from such people
A desire for more solitude
You might want to quit your job, your relationship, and/or your family (I suggest not to be hasty here, because if it is a true awakening, you will later realize that changing these external influences won't help you, although it may seem so in the short term - however, if you are in a relationship that is causing a threat to your life, please take the right actions).
Second Stage of Awakening
Lack of judging yourself and others
Letting things happen without trying to make them happen
Feeling like purging your life (all the conditioned way of life)
Confused, alone (not lonely), and an existential fear, which later will become the grace
There is a hunger for authenticity and truth.
Profoundly wanting to understand who you are, at any cost
You enjoy being in solitude (don't worry, it changes later)
You begin to notice your negative conditioning and want to heal them (not for any further achievement, but just out of curiosity and love) - this is a noteworthy distinction from ego vs true spiritual awakening
Energetic changes occur rapidly within you, that even if you feel you don't want to continue this path, you will be pushed into it (The truth is you won't be able to resist, these energies are too much to resist, your only option is to go with it, not against it)
You see through illusions of your life and society.
You become more sensitive.
Your intuition gets heightened
Deeper stages of Awakening
Feeling of oneness and unity (an actual experiencing, not just a concept)
An intense presence - and any other moment without this presence becomes suffering, NOW is slowly becoming your attention's anchor
Healing that occurs naturally, beyond your cognitive and emotional aspects. At this stage, you would be stabilizing and integrating your true nature into all aspects of your life
You need less attention or crowd or public situations. Instead, you are content to watch, assist and help others without any bandwagon. Note how this is precisely the opposite of the ego, which wants more attention, validation, recognition, and power
Increased inner peace
Feeling drawn to nature and pets/animals (as these are energetically more grounded)
Feeling extremely grounded, a stable core, a renewed consciousness from the source (I am sorry, I am losing words here)
Increased empathy and intuition
There is no desire to change and be better than where you are, you are fulfilled, and any action that arises is fine; it is a distinctive feeling
Doing less and more of "being"
Change and heal people around them, intentionally or unintentionally.
Spontaneous actions and actions without expectations
There are numerous physical symptoms that happen during awakening that sometimes feel scary and difficult to deal with:
Disturbances in sleep pattern - Either too much sleep or very little sleep. There are energetic shifts going on in the body, and body and mind need some time to settle
Decreased immune system for some time with physical illnesses (may be) and then increased immune system
Discovering food intolerances - suddenly turning to a vegetarian diet or vice versa, you seem to be aware and operate through body and body dictates what you eat (this is how it should always be)
Intensified senses - all of the five senses - vivid colors and increased sensitivity to sounds
Vivid and Bizarre dreams - Dreams are an excellent healing methodology; it is amazing how we have AHA moments in dreams
Changes in appetite and weight - Sudden losing or gaining of weight
Fluctuations in energy - Sudden energy surges - sometimes feeling extraordinarily active and sometimes extremely fatigued
In deeper stages, the body feels blissful
Sudden pains and aches that come and go for no reason
Tingling and crackling sensations along the spine, and sometimes, sudden heat or cold along the spine and in other body parts
Lot of other Kundalini symptoms
I hope these provide you with information on most of the symptoms through the awakening process, and there are more than these. Once you begin awakening, it is a lifelong journey. Realization of true nature happens spontaneously; in an instance, however, integrating this understanding into all our lives is an ongoing process. We all proceed at our own pace, but at this stage, there is no hurry to be in any other place, so anything that is happening is experienced as vibrancy - out of curiosity and discovery. Presence becomes benevolent.