Breakdown of Если постоянно недосыпать, можно серьёзно заболеть.
можно
one may, it is allowed
постоянно
constantly
если
if
серьёзно
seriously
Questions & Answers about Если постоянно недосыпать, можно серьёзно заболеть.
How does the prefix недо- change the meaning of the verb here?
The prefix недо- indicates that an action is performed insufficiently or below a normal, healthy requirement. Added to the root of спать (to sleep), it creates недосыпать, which means to not get enough sleep or to be sleep-deprived.
Is there a difference between the single word недосыпать and writing it as two words, не досыпать?
Yes, there is a very important difference! As a single word, the prefix недо- means doing something insufficiently (a lack of sleep). If written as two words (не досыпать), it uses the negative particle не with the prefix до- (which means to complete an action), meaning to not finish sleeping or to wake up before you were supposed to.
Why is недосыпать imperfective while заболеть is perfective?
Недосыпать is imperfective because the adverb постоянно (constantly) shows it is a repeated, ongoing habit. Заболеть is perfective because it focuses on the sudden result or consequence (getting sick) of that bad habit.
Why isn't there a subject like ты (you) in either half of this sentence?
This is an impersonal construction used to state a general truth. Using если directly with an infinitive (недосыпать), followed by можно plus another infinitive (заболеть), creates a rule that applies to absolutely anyone. In English, we usually translate this using the general 'you' or 'one'.