A mosquito in real life would not let you sleep. As per Islam, if you see a mosquito in a dream, it could have different meanings depending upon the context.
1- According to Ibn Sirin رحمة الله عليه, the greatest dream interpreter of Islam, a mosquito in a dream means a weak person/humiliation and disgrace.
2- Fighting with a mosquito in a dream represents a tussle with a weak person.
3- Seeing a lot of mosquitos attacking in a dream is a sign that a lot of ordinary people will talk about him which will cause him a loss of repute.
4- Seeing a mosquito entering the nose or ear causing pain in a dream means that the dreamer will face sadness and pain from an ordinary and weak person.
5- If the mosquito is not coming out from the ear or nose in a dream, it is a sign of being involved in hectic and tough work.
6- Ibrahim Karmani رحمة الله عليه, seeing a lot of mosquitos entering the house is a sign of sadness and sorrows.