Interruptions to a Bracha
When is a new Bracha Rishona required?
- As long as one didn’t have a interruption in one's train of thought (Hesech Hadaat), which will be clarified below, one doesn’t need to make a new Bracha Rishona. However, if one made a Bracha Achrona, and one wants to eat again a new Bracha Rishona is needed. 
- If one if planning on having coffee or tea for a length of time as one sits and learns, one Shehakol covers all the cups one drinks even there’s a long break between cups. 
- If one made a Bracha Rishona and waited 72 minutes one doesn’t need to make another Bracha Rishona. 
- If one made a Bracha Achrona only because one was afraid that Shuir Ikul would pass and one has intent to continue eating afterwards, one doesn’t need a new Bracha Rishona when one continues to eat. 
- One who went to the bathroom in the middle of a snack need not recite a new bracha upon returning. 
Interruption of a Bread Meal
- If one Davened in middle of a meal it’s not considered an interruption. 
- Sleeping in middle of a meal isn’t considered an interruption except that one needs to wash Netilat Yadayim. 
- During a meal, if one touches areas of one's body which are supposed to be covered, one should wash Netilat Yadayim without a Bracha. 
- Someone who went to the bathroom during a meal isn’t considered an interruption rather one should just make Netilat Yadayim and Asher Yatzer afterwards. 
- If one said Shir HaMaalot it is not considered an interruption of the meal. 
- Beiur Halacha 190 s.v. Acher, Vezot HaBracha (pg 53, chapter 5)
- Sh”t Yechave Daat 6:11, Sh”t Yabia Omer O”C 6:27, Sh”t Chazon Ovadyah 1:18, Yalkut Yosef (vol 3 pg 224)
- Yalkut Yosef (vol 3, pg 227)
- Yalkut Yosef (Kitzur S”A 178:18)
- Rama OC 178:7. Even though the Biur Halacha 178:7 writes that for a non-bread meal going to the bathroom would be an interruption, the Piskei Teshuvot 178:7 holds that nowadays when we have bathrooms indoors we don't recite a new bracha after going to the bathroom. Regarding Sephardim, even though Rav Ovadia Yosef (Halichot Olam (vol 1 pg 44) and codified in Yalkut Yosef (vol 3 pg 330)) held that one should recite a bracha if one goes to the bathroom in the middle of a meal, later he retracted as is recorded in Yalkut Yosef (Brachot 5771 version, 178:26). Halacha Brurah 178:23 agrees.
- Tosfot Pesachim 102a s.v. vaakru proves from the gemara that if a party left the house to daven it isn't considered an interruption of a meal that davening in the middle of a meal isn't considered an interruption at all. Even though one can't eat while one is davening, nonetheless, it isn't an interruption. Yalkut Yosef (vol 3 pg 228) codifies this.
- Yalkut Yosef (vol 3 pg 229)
- Yalkut Yosef (vol 3 pg 331)
- Yalkut Yosef (vol 3 pg 330)
- Piskei Teshuvot 179:4