The deaths of all but one of the crew of the science vessel USS Brattain, who lost the ability to dream and killed one another while trapped in a Tyken's Rift.
In The Next Generation episode Night Terrors, the Enterprise-D finds the missing Brattain adrift in a binary star system. Its crew of thirty-four are dead by violence, apparently at each other's hands. The only survivor is a catatonic Betazoid adviser, Andrus Hagan.
The Enterprise then finds it cannot leave: both ships are caught in a Tyken's Rift, which drains energy and can only be broken by a large explosion. Within days the crew grow irritable, frightened and prone to hallucinations. Crusher finds that nobody except Troi is reaching dream sleep, and Troi's own dreams are a repeating nightmare.
Troi realises the dream is a message from another ship trapped across the rift, whose telepathic signals are disrupting everyone else's sleep. Its crew are asking for hydrogen. Data, unaffected, releases it on cue, the aliens supply the other element, and the blast frees both ships.