La falta de descanso empeora mi cansancio.

In this sentence, falta means lack / absence, not fault.

• La falta de descanso = the lack of rest or not getting enough rest.
• It does not mean the fault of rest or rest’s fault.

So:

• falta de algo → lack of something
• Es culpa mía → It’s my fault (you wouldn’t use falta here for “fault”).

Spanish very often uses a definite article (el, la, los, las) where English would drop the.

• La falta de descanso empeora mi cansancio.
  Literally: The lack of rest worsens my tiredness.

If you drop la and say Falta de descanso empeora mi cansancio, it sounds incomplete or like a headline or note, not normal full-sentence speech.

In standard speech/writing, you want the article:

• ✅ La falta de sueño afecta a mucha gente. = Lack of sleep affects many people.

The subject is la falta de descanso.

Breakdown:

• La falta de descanso → subject (singular)
• empeora → verb (3rd person singular, present)
• mi cansancio → direct object

So the structure is: > [The lack of rest] [worsens] [my tiredness].

The verb must agree with the subject in number.

• Subject: la falta de descanso → singular
• So we use empeora (3rd person singular).

If the subject were plural, the verb would be plural:

• Las malas noches empeoran mi cansancio.
  (Bad nights worsen my tiredness.)

Here las malas noches is plural → empeoran.

Empeora is the third person singular present of the verb empeorar, which means:

• to make worse (transitive)
• to get worse (intransitive)

In this sentence it’s transitive:

• La falta de descanso empeora mi cansancio.
  The lack of rest makes my tiredness worse.

Other forms:

• Yo empeoro (I make worse / I get worse)
• Tú empeoras
• Él/Ella empeora
• Nosotros empeoramos, etc.

Both are possible, but the nuance changes slightly.

• mi cansancio = my tiredness → personal, specific to you.
• el cansancio = the tiredness / tiredness in general or in a more generic sense.

So:

• La falta de descanso empeora mi cansancio.
  Emphasizes how your own tiredness gets worse.
• La falta de descanso empeora el cansancio.
  Sounds more general, like a statement about people’s tiredness overall.

All three relate to being tired, but they have different typical uses:

• cansancio

  • General tiredness / exhaustion (physical or mental).
  • Tengo mucho cansancio. = I’m very tired / exhausted.

• sueño

  • Sleepiness / the need to sleep.
  • Tengo mucho sueño. = I’m very sleepy.

• fatiga

  • Can mean tiredness/exhaustion, but in everyday speech can sound more formal or medical, or even like nausea in some contexts.
  • More common in medical / formal language: fatiga crónica (chronic fatigue).

In your sentence, cansancio is natural because it’s about a general state of being worn out.

Both patterns exist, but they’re not always interchangeable.

• falta de descanso = lack of rest (rest as a noun)
• falta de descansar = not resting / lack of the action of resting (rest as a verb)

La falta de descanso is the most idiomatic here; it feels more natural and general.
La falta de descansar would be understood but sounds more like you’re focusing on the act of resting as an activity you don’t do, rather than rest as a condition.

Think of the English difference:

• The lack of rest (more natural)
• The lack of resting (possible but less common).

You can, but it sounds slightly less natural than La falta de descanso in many contexts.

Nuance:

• La falta de descanso: broader – includes not sleeping well and not taking breaks, not relaxing, etc.
• La falta de dormir: more literal – specifically not sleeping enough.

Both are grammatically correct, but La falta de descanso is more standard and flexible.

Del = de + el, so del descanso means of the rest, referring to some specific rest we know about.

• falta de descanso = lack of rest (rest in general)
• falta del descanso = lack of the rest (a particular rest already mentioned or known)

In your sentence we mean rest in general, so we use:

• ✅ La falta de descanso empeora mi cansancio.

It’s neutral. You can use it:

• In everyday conversation:
  La falta de descanso empeora mi cansancio, la verdad.
• In more formal or written contexts:
  La falta de descanso empeora el cansancio en los pacientes.

It doesn’t sound slangy or overly technical.

Some common, more conversational alternatives:

• No descansar empeora lo cansado que estoy.
• No descansar me deja todavía más cansado.
• No descansar me cansa aún más.

These keep the same idea but sound more like everyday spoken Spanish.

• falta → FAHL-ta

  • f as in English, a like father, l clear, t dental (tongue against teeth), final a like father.

• descanso → des-KAN-so

  • de like deh, s always like English s (never z), ca = ka, nso = n-so.

• cansancio → kan-SAN-thyo (Peninsular / Spain Spanish)

  • c before i is pronounced like English th in think in most of Spain.
  • So -cio = -thyo.

In Latin America, cansancio is pronounced kan-SAN-syo (with an s sound instead of th), but in Spain you’ll typically hear the th sound.