Quand je suis fatigué, je confonds facilement le mardi et le jeudi.

In French, many physical or emotional states are expressed with être rather than avoir.

So:

• je suis fatigué = I am tired

Using j’ai fatigué would not mean I am tired. It would sound like I tired someone/something out, because fatiguer is also a verb meaning to tire.

This is similar to:

• je suis prêt = I am ready
• je suis malade = I am sick

So in this sentence, suis is the normal and correct choice.

Fatigué agrees with the speaker’s gender.

• A male speaker says je suis fatigué
• A female speaker says je suis fatiguée

In speech, you usually do not hear the difference clearly, but in writing it matters.

If several people were speaking, you could also get:

• nous sommes fatigués for a masculine or mixed group
• nous sommes fatiguées for an all-female group

Yes. Quand can mean when in both statements and questions.

In this sentence:

• Quand je suis fatigué = When I’m tired

As a question:

• Quand pars-tu ? = When are you leaving?

So quand works both as:

1. a question word
2. a conjunction introducing a time clause

Here it is a conjunction.

Yes, in this sentence lorsque would also work:

• Lorsque je suis fatigué, je confonds facilement le mardi et le jeudi.

Both mean when.

The main difference is style:

• quand is very common and natural in everyday speech
• lorsque is a bit more formal or literary

For normal conversation, quand is usually the more natural choice.

Because the subject is je, and the verb confondre must be conjugated to match it.

Present tense of confondre:

• je confonds
• tu confonds
• il/elle/on confond
• nous confondons
• vous confondez
• ils/elles confondent

So:

• je confonds = I confuse / I mix up

The -s ending is the normal je form here.

Here, confondre means to confuse or to mix up.

So:

• je confonds le mardi et le jeudi = I mix up Tuesday and Thursday

It does not mean that Tuesday becomes Thursday. It means the speaker has trouble telling them apart or remembers the wrong one.

A very common pattern is:

• confondre A et B = to confuse A and B

For example:

• Je confonds souvent leurs prénoms. = I often mix up their first names.
• Il confond le sucre et le sel. = He mixes up sugar and salt.

French normally uses the definite article before days of the week when talking about them as nouns.

So:

• le mardi = Tuesday
• le jeudi = Thursday

After confondre, the days are being treated as things being confused with each other, so the articles are natural.

French often uses articles in places where English does not:

• J’aime le café. = I like coffee.
• Le lundi est difficile. = Monday is hard.

Here, le mardi et le jeudi is simply the normal French way to say Tuesday and Thursday in this structure.

Yes, but not in this sentence.

In French, le + day of the week can have two main meanings depending on context:

1. the day itself

   • Je confonds le mardi et le jeudi.
   • I mix up Tuesday and Thursday.

2. every/on that day

   • Le mardi, je travaille à la maison.
   • On Tuesdays, I work from home.

In your sentence, it clearly means the two days themselves, not a repeated habit.

Facilement is an adverb, and in French adverbs often come after the conjugated verb.

So:

• je confonds facilement = I easily confuse / I easily mix up

This word order is very natural in French.

Compare:

• Il parle bien. = He speaks well.
• Nous comprenons vite. = We understand quickly.

French adverb placement does not always match English exactly, so it is best to learn common patterns rather than translate word for word.

It would sound less natural in standard French. The version with the articles is better:

• je confonds facilement le mardi et le jeudi

French usually prefers the articles here because mardi and jeudi are specific nouns, not bare labels.

A learner may want to drop the articles because English says Tuesday and Thursday, but French generally does not.

Yes, that is also correct.

You can say:

• je confonds le mardi et le jeudi
• je confonds le mardi avec le jeudi

Both mean that you mix them up.

A small nuance:

• confondre A et B is very common and direct
• confondre A avec B explicitly highlights A with B

In many everyday situations, they are interchangeable.

The comma separates the introductory time clause from the main clause:

• Quand je suis fatigué, = introductory clause
• je confonds facilement le mardi et le jeudi. = main clause

In English, you often do the same:

• When I’m tired, I easily mix up Tuesday and Thursday.

The comma makes the sentence easier to read. In short sentences, punctuation rules can vary a little, but here the comma is completely natural.

Yes, it is in the present tense:

• je suis
• je confonds

In this context, the present tense describes a general tendency or repeated situation:

• When I’m tired, I mix up Tuesday and Thursday

So it does not refer to just one specific moment unless context makes that clear. It sounds like a habitual or typical reaction.

If only the speaker changes from male to female, the main sentence stays the same except for fatiguée:

• Quand je suis fatiguée, je confonds facilement le mardi et le jeudi.

Speaking to several people informally does not change anything here, because there is no you form in the sentence.

If you wanted to say When we are tired, we easily mix up Tuesday and Thursday, then it would be:

• Quand nous sommes fatigués, nous confondons facilement le mardi et le jeudi.

And for an all-female group:

• Quand nous sommes fatiguées, nous confondons facilement le mardi et le jeudi.