You wake up in trance, which in deep sleep if done , in and out of counciousness can result in the feeling of re-entering your body, your astral body can hover mildly above the material body.
If you do in day time, try to not fall asleep, as the buzz either from your astral body or trance will wake you up violently, which results in head aches and other pains. This is not healthy and if really disturbed from a very deep trance, it can lead you to real health issues.
Secondly when you are doing ap, the movement is made by intent not by any other mechanism. If the astral body has too much bio electricity you will not be able to move and you will be fixated above the body.
Please understand the difference of ap. And simple trance buzzing. Both can feel brutal yet are different. You can feel the trance buzz but you may not have the ap. Sidhhi developing yet.
Having too little bio electricity will lead you to not be able to travel far, and this is in terms of meters of a couple hundred before being snapped back in your body as the electricity runs out like fuel outside your body structure.
Anyway, either in trance or ap. Never stress yourself or tension your intent too hard. This will lead to build up energy that will remain static, either in organs or parts of the body. That's why if you meditate before sleeping I advise for circulation of energy right after. Sleeping fixated in a static way on energy will also amplify and fixate it. Energy must be moving and be alive, not static.
To practice successfully ap., you definitely must train at night, not day time and have the electric body established and really strong with no leaks. Naturally the overflow of bio electricity in sleep or meditation at night will snap you out of your body when the natural rising of currents in the body happen. You may learn by this indirect way to do it directly under your control.
To further point something of importance in ap, is also feeling the octaves of the bodies vibration along your body. From the base to the heart if you focus in the literal vibration and own soul engine, it will propel you outside to travel.
And to really make another point, when you leave the body in a full on ap. , it is absolutely no different than literally departing your body with all of your senses. You will also feel the nature of the material. The hardest thing is the shock of the mind which will return to your body. Having complete control also happens with experience in this, so it is not a simple development but something of training to be able to fulfil the use of this.