Nattsynet påvirkes av lysforurensningen.

The -s marks the passive voice in Norwegian.

• påvirker = affects (active)
• påvirkes = is affected / gets affected (passive)

So:

• Nattsynet påvirkes av lysforurensningen. = Night vision is affected by the light pollution.

A very natural active version would be:

• Lysforurensningen påvirker nattsynet. = The light pollution affects night vision.

Norwegian often uses this -s passive instead of a separate verb like is affected.

Nattsynet is the definite singular form: the night vision.

• nattsyn = night vision
• nattsynet = the night vision

In Norwegian, definiteness is usually added to the end of the noun:

• en bil = a car → bilen = the car
• et hus = a house → huset = the house
• et nattsyn is not really how this word is normally used, but grammatically nattsynet is the definite neuter form

In this sentence, the speaker is talking about night vision as a known or specific thing, so the definite form is natural.

Because lysforurensning is a noun in the common gender (en-word), and -en makes it definite singular.

• lysforurensning = light pollution
• lysforurensningen = the light pollution

So the structure is:

• en lysforurensning → lysforurensningen

Even though English often says just light pollution without the, Norwegian may still use the definite form depending on context. Here it sounds like a known phenomenon or the particular light pollution being discussed.

Here av means by in a passive construction.

• påvirkes av lysforurensningen = is affected by the light pollution

This is very common in Norwegian passive sentences:

• Boken ble skrevet av henne. = The book was written by her.
• Huset eies av familien. = The house is owned by the family.

So in this sentence, av introduces the thing causing the effect.

Yes, it is passive.

Passive version:

• Nattsynet påvirkes av lysforurensningen. = Night vision is affected by the light pollution.

Active version:

• Lysforurensningen påvirker nattsynet. = The light pollution affects night vision.

Both are correct. The passive version focuses more on nattsynet, while the active version focuses more on lysforurensningen.

Norwegian forms compounds very freely, much like English.

1. nattsyn

This is made from:

• natt = night
• syn = sight/vision

Together:

• nattsyn = night vision

The extra -t- is just part of how the compound is formed from natt + syn.

2. lysforurensning

This is made from:

• lys = light
• forurensning = pollution

Together:

• lysforurensning = light pollution

Then the definite endings are added:

• nattsyn → nattsynet
• lysforurensning → lysforurensningen

Because Norwegian often expresses this idea with a single passive verb form.

English:

• is affected

Norwegian:

• påvirkes

So instead of using a separate auxiliary like is, Norwegian can build the passive directly into the verb by adding -s.

There is also another possible passive style in Norwegian using bli:

• Nattsynet blir påvirket av lysforurensningen.

This also means Night vision is affected by the light pollution, though the -s passive version is shorter and very common in formal or general statements.

It is present tense passive.

• påvirker = affects
• påvirkes = is affected / gets affected

So the sentence describes something that happens generally or currently:

• Nattsynet påvirkes av lysforurensningen. = Night vision is affected by the light pollution.

This can sound like a general fact, which is very common in explanations, science, and formal writing.

A rough guide for English speakers:

• Nattsynet ≈ NAHT-see-neht
• påvirkes ≈ POH-veer-kes
• av ≈ ahv
• lysforurensningen ≈ LEES-fo-roo-REHN-sning-en

A few useful pronunciation notes:

• y in Norwegian is not the same as English y. It is a rounded vowel, somewhat unfamiliar to English speakers.
• på has an å sound, like a broad aw/o sound.
• Norwegian compounds are usually pronounced as one word.
• The stress often falls early in the word, but exact pronunciation varies somewhat by dialect.

If you are learning standard Eastern Norwegian pronunciation, listening to native audio is especially helpful for y, å, and consonant clusters like rn, rs, and sn.

Yes, that is possible in some contexts, but it changes the feel.

• Nattsynet påvirkes av lysforurensningen
  = The night vision is affected by the light pollution

• Nattsyn påvirkes av lysforurensning
  = Night vision is affected by light pollution

The version without definite endings sounds more general and abstract, which is often natural in scientific or textbook style. The version with definite endings can sound more like the speaker is referring to a known phenomenon or a specific context.

So both can work, but the sentence you were given is not unusual.

It sounds fairly neutral, informative, and a bit formal.

Because it uses:

• a passive verb (påvirkes)
• abstract nouns (nattsynet, lysforurensningen)
• a factual tone

it feels like something you might see in:

• a textbook
• an article
• a scientific explanation
• an informational website

In everyday spoken Norwegian, people might also say the more active version:

• Lysforurensning påvirker nattsynet.

That often sounds a little more direct and conversational.