The incident happened yesterday morning (Thursday, January 16), police added.
A Sussex Police spokesperson said: “Police are investigating after a man was found dead at a property in Brighton.
“Emergency services attended Upper Hollingdean Road around 10am on Thursday (January 16) after concerns were raised for the welfare of a 41-year-old man.
“He was found inside the address, and was sadly confirmed deceased at the scene.
“The death is currently being treated as unexplained and an investigation is under way to establish the circumstances around it.”
Police added that a 49-year-old man from Hove has been arrested on suspicion of murder and taken into custody while enquiries continue. Both men are believed to be known to each other, police said.
DCI Mark Cullimore said: “There will be increased police activity in the area as we gather information and evidence to assist us in establishing what has led to this man’s death.
“I’d like to thank residents and the wider public in advance for their patience while we carry out these enquiries and ask if anyone has any information or concerns relating to this matter that they speak to an officer or get in touch with us.”
Anyone with information can contact police online or by calling 101 quoting Operation Marshgate. Alternatively, information can be submitted anonymously via the independent charity Crimestoppers on 0800 555 111.

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Police at the scene. Picture: Sussex News and Pictures Photo: Sussex News and Pictures

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Police at the scene. Picture: Sussex News and Pictures Photo: Sussex News and Pictures

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Police attended the scene. Picture: Sussex News and Pictures Photo: Sussex News and Pictures