A Crawley home invader attacked his victim with a bat.
Police are investigating an aggravated burglary in the early hours of Thursday (March 21) at a property in Gresham Walk.
A police spokesman said: “Around 12.45am a man came into the property and attacked a 19-year-old man with a bat.
“He was treated at hospital for head and arm injuries.”
The attacker, who fled the scene, is described as white with blonde hair and in his 20s.
Detective Inspector Colin Garman said: “The victim has some serious but not life threatening injuries and remains in hospital.
“We are appealing to anyone who saw someone enter the property or was seen running away to contact us.”
Contact police online quoting serial 55 of 21/03 or call Crimestoppers anonymously on 0800 555 111.