A lot of red dots on the hands overnight may be mosquito bites, eczema, allergic rashes and other causes. 1. Mosquito bites: summer and fall seasons, mosquitoes, such as mosquito bites at night, can lead to a lot of small red dots on the hands overnight, can also be accompanied by a certain degree of itching, pain. 2. Eczema: is caused by a variety of internal and external factors, such as neuropsychiatric factors, endocrine and metabolic changes, food and other causes of superficial dermal and epidermal inflammation. Acute lesions are dominated by herpes papules, and chronic lesions are dominated by mossy changes, which can be accompanied by itching and other symptoms. It can also lead to a lot of small red dots on the hands overnight. 3. allergic rash: also known as drug rash, is one of the more common adverse drug reactions, often manifested as a red macular rash, maculopapular rash, can also be a wind ball like, accompanied by itching, but also accompanied by nausea, vomiting, abdominal pain, diarrhea, respiratory distress and other symptoms. It can also lead to a lot of small red dots on the hands overnight. There are many other causes of red dots on hands overnight, which should be taken seriously, and it is recommended to consult a doctor in time to identify the cause of the disease and follow the doctor’s instructions for further treatment or therapy.