When you are afraid to go to sleep or feel lonely & depressed recite this du'aa:

In the Name of Allah Most Gracious and Most Merciful

When you are afraid to go to sleep or feel lonely & depressed recite this du'aa:

أَعُوذُ بِكَلِمَاتِ اللهِ التَّامَّاتِ مِنْ غَضَبِهِ وَعِقَابِهِ، وَشَرِّ عِبَادِهِ، وَمِنْ هَمَزَاتِ الشَّيَاطِينِ وَأَنْ يَحْضُرُونِ

I seek refuge in the Perfect Words of Allah from His anger and His punishment, from the evil of His slaves and from the taunts of devils and from their presence.

Abu Dawud 4/12. See also Al-Albani, Sahih At- Tirmidhi 3/171.