Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain bleeding from the gums is a sign of Periodontal disease and if it happen specially at night it can be due to a few conditions like mouth breathing habit leading to dryness of mouth and gums and irritation can lead to bleeding of already diseased gums.. Other reason can be allergic reaction to some food or medicine which is taken specifically at night.. One another reason for bleeding gums can be Vitamin C deficiency and it can happen to him as he is already on dieting and might be deprived f nutrition.. You should consult a Periodontist and get evaluated and get a proper Scaling, Sub-gingival curettage or flap curettage done to remove the infection.. Maintain a good oral hygiene,use concentrated solution of mouthwash for gargles and do proper brushing of teeth as well as flossing as well as a course of antibiotics like amoxicillin and metronidazole can be taken.Take a chewable Vitamin C tablet for 15 days, add more of citrus fruits in your diet.. In case of mouth breathing habit you can apply a vertical strip of micropore tape over the closed lips before sleeping to prevent mouth breathing.. If there is allergic reaction avoidance of the particular food will help.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..