Can sleeping too much be harmful? during school holidays, i can sleep at least 10 hours every night. is it normal?

May be, may be not.: You may be one of the so-called "long sleepers" which is considered a normal variant, or you may be "catching up" on volitional sleep deprivation (not giving yourself enough sleep) during the school nights.

Sleep Concern: I understand your concern for sleeping too much. At your age of 31, generally sleep is 7-8 hours It is OK to sleep for 2-3 days if you have been exhausted, overwhelmed or frustrated in school. Let Wise Person in you ask for stresses of: •School •Work •Finances •Relationships/ Marriage •Separation/Divorce •Parenting •Loneliness •Boredom See a Therapist to discuss these and improve your functioning