A noun that describes someone who loves sleeping, or habitually sleeps in a lot, especially in the morning, is dormiglione (masculine, plural dormiglioni) or dormigliona (feminine, plural dormiglione) in Italian. The best translations are sleepyhead and late riser.
Today’s word is the combination of the verb dormire (to sleep) and the suffix -one which is added to verbs to create nouns denoting “one who often does X” or “one who is characterised by X”.
There are various words in Italian that follow this structure such as, for example, mangione (big eater, from the verb mangiare – to eat) or guardone (voyeur, from the verb guardare – to look, to watch).
Svegliati, dormiglione! Abbiamo un sacco di cose da fare oggi.
Wake up, sleepyhead! We have a lot of things to do today.
By contrast, if you want to describe someone who is an early riser, you can use the words mattiniero (masculine) and mattiniera (feminine).
Io sono assai mattiniero, mentre lei è una gran dormigliona.
I am a real early bird, while she is a late riser.
More rarely, dormiglione is used figuratively to describe a lazy or inactive person. Other synonyms you will hear more in Italian are pelandrone and pigrone.
Finally, in zoology, it is also the name given to the sleeper goby, a type of fish that spends long periods immobile on the sea floor.