What is the reason for seeing scary dreams after reciting morning and pre-sleep adhkar (supplications), and not seeing anything when not reciting them? And can Satan approach someone who recites adhkar, even though the Messenger of Allah, peace and blessings be upon him, said: "If you recite the adhkar, there will be a barrier between you and Satan"? And what is the solution for these recurring dreams?

Firstly, it has been established that dhikr (remembrance of Allah) protects a servant from Satan, especially Ayatul-Kursi, which protects a sleeper from devils until morning, as narrated in the hadith of Abu Hurairah in Sahih Al-Bukhari. Furthermore, the remembrance of Allah, the Mighty and Majestic, is the most fortified protection a servant can have against Satan, as mentioned in the hadith. As for frightening dreams, they can be overcome by adhering to obedience to Allah, and by increasing dhikr and recitation of the Qur’an, especially Al-Fatiha, Ayatul-Kursi, and the two Mu'awwidhatayn (Surahs Al-Falaq and An-Nas). One must beware of sins because they bring about these nightmares, in accordance with His, the Almighty’s, saying: ﴿And whoever turns away from My remembrance – indeed, he will have a suffocating life﴾ [Taha: 124].

If frightening dreams come after performing adhkar, then this is a deception from Satan, making one imagine that dhikr is their cause. So, you must strengthen your trust in Allah, rely on Him, and have a good opinion of Him. What you mention are merely dreams, and seeking refuge and spitting will repel their harm, as in the hadith: "If any of you sees a dream that he dislikes, he should spit to his left three times and seek refuge with Allah from its evil, for it will not harm him."

And know that the effect of dhikr and seeking refuge varies according to the faith of the one remembering, their conviction, and the presence of their heart. The Prophet, peace and blessings be upon him, said: "Supplicate to Allah while you are certain of being answered, and know that Allah does not answer a supplication from a heedless, inattentive heart." So, supplication with a heedless heart has no effect. And supplications and seeking refuge are like a weapon; if the weapon is complete and the supplicator is strong, the effect will be achieved, otherwise it will not.