This pattern is used to say that if a certain situation or action continues, a bad result will occur. It often carries a sense of criticism or warning. It is formed by taking the て-form of a verb, adding いて (the て-form of いる), and then は. For example, 食べて + いて + は becomes 食べていては. The は is often pronounced as 'wa' but written as は. In speech, では sometimes becomes じゃ, but for ていては, the contraction to てちゃ is not standard; stick with ていては for clarity, especially in writing or formal speech. This pattern is used in both spoken and written Japanese, but it is more common in written or slightly formal contexts. In casual conversation, you might hear ていちゃ or てちゃ in some dialects, but avoid using them unless you are sure. The meaning is often 'if you keep doing ~' or 'if you remain in a state of ~', leading to a negative outcome. For example, if you keep staying up late, you'll get sick. The pattern emphasizes that the continuation of the action is problematic. It can also be used with negative consequences stated after the は clause. The result is often expressed with a negative expression or a suggestion to change behavior.