Learn Swedish: Jag älskar att sova i sängen.

Att is the infinitive marker, just like "to" in English ("to sleep"). After att, you must use the base form of the verb (the infinitive). For most Swedish verbs, including sova, this base form ends in an "-a". You cannot use the present tense sover here.

Why doesn't älskar have an att in front of it?

Älskar is the main verb of the sentence, showing what is happening right now ("I love"). It is in the present tense, which usually ends in "-r" in Swedish. You only use att before the second verb in the sentence when it acts as an infinitive, like att sova ("to sleep").

Why is it sängen instead of just säng?

Säng is an "en-word" meaning "bed" or "a bed". To say "the bed", Swedish adds the definite ending -en to the end of the noun, making it sängen.

How do Swedes usually pronounce att sova in everyday speech?

While att is written with an "a" and two "t"s, in everyday spoken Swedish it is almost always pronounced like the Swedish letter "å" (similar to the "o" in the English word "core"). So you will usually hear native speakers say "å sova" instead of "att sova".