Before you sleep, read 'Ayat al-Kursi'

Abu Hurairah reported that the Messenger (peace and blessings of Allaah be upon him) said,
"When you are about to sleep recite Ayatul Kursi till the end of the Verse for there will remain for you a protection from Allaah and no devil will draw to you until morning." [Saheeh al-Bukhaaree]

Ayat al-Kursi is verse 255 of the second chapter (surah) of the Holy Quran, Surat al-Baqarah (the chapter of the cow).

'Allahu la ilaha illa huwa, Al -Haiyul-Qaiyum La ta'khudhuhu sinatun wa la nawm lahu ma fi as-samawati wa ma fil-'ard Man dhal-ladhi yashfa'u 'indahu illa bi-idhnihi Ya'lamu ma bayna aydihim wa ma khalfahum wa la yuhituna bi shai'in min 'ilmihi illa bima sha'a Wasi'a kursiyuhus-samawati wal ard wa la ya'uduhu hifdhuhuma wa Hu wal 'Aliyul-Adheem'

"Allah! There is no god but He - the Living, The Self-subsisting, Eternal. No slumber can seize Him Nor Sleep. His are all things In the heavens and on earth. Who is there can intercede In His presence except As he permitteth? He knoweth What (appeareth to His creatures As) Before or After or Behind them. Nor shall they compass Aught of his knowledge Except as He willeth. His throne doth extend Over the heavens And on earth, and He feeleth No fatigue in guarding And preserving them, For He is the Most High. The Supreme (in glory)." [Surah al-Baqarah 2: 255]