This article compares the use of the verbs to eat and to sleep in four deep Latgalian or Non-Selonian sub-dialects of the High Latvian dialect – Ziemers and Veclaicene from North-East Vidzeme, and Driceni and Gaigalava from Latgale. When studying the deep Latgalian sub-dialects, one faces the challenge that the same linguistic unit tends to differ, both phonetically and morphologically, not only within one dialect or group of sub-dialects, but also within one sub-dialect or neighbouring sub-dialects. Typically, sub-dialect dictionaries and dialect atlases provide the transposed form as the basic unit, thereby losing the original specific phonetic and morphological form of the variant spoken in the sub-dialect in published sources. Furthermore, the survey of the Latvian Dialect Atlas (1954) does not require a full paradigm of present tense forms for many verbs, such as the word to sleep. The purpose of this article was to identify the common and distinct phonetic and morphological characteristics of the verbs to eat and to sleep, which could be useful in determining both isoglosses and regiolect boundaries for future sub-dialect studies. The language material was obtained through analysing the responses to questions 228 and 230 of the survey of the Latvian Dialect Atlas: "How is the verb to eat conjugated in the present, past, and future tenses?" and "How is the verb to sleep conjugated in the present tense?" Additionally, the authors used material collected by themselves and other recent sources. By comparing the verb forms of to eat and to sleep in the simple present, past, and future tenses, as well as the supine forms in Ziemers, Veclaicene, Driceni, and Gaigalava sub-dialects, the authors identified both common features of the deep Latgalian sub-dialects of the High Latvian dialect and significant phonetic and morphological phenomena that differentiate these sub-dialects from one another. Descriptions of specific sub-dialects, represented as language units, with precise phonetic transcriptions and the inclusion of both contemporary and earlier versions of these descriptions, are crucial for developing a more comprehensive characterisation of the dialects. For a more thorough linguistic analysis, it is important to obtain language material from informants of different ages, as well as speakers of the same sub-dialect residing in different locations, each with their own linguistic experiences.