text: sleepless ( the x - files ) " sleepless " is the 4th episode of the second season and 28th overall of the science fiction television series the x - files . the episode first aired in the united states on october 7 , 1994 on fox . the episode was written by supervising producer howard gordon , and directed by rob bowman . " sleepless " earned a nielsen rating of 8 . 6 and was viewed by 8 . 2 million households . the episode received mostly positive reviews from critics . the show centers on fbi special agents fox mulder ( david duchovny ) and dana scully ( gillian anderson ) who work on cases linked to the paranormal , called x - files . in this episode , mulder is assigned a new partner , alex krycek ( nicholas lea ) . the two investigate a case where doctors and soldiers who were part of a sleep deprivation experiment are being killed off . " sleepless " featured what would become the recurring character of alex krycek , portrayed by nicholas lea . krycek would progress from mulder 's partner to one of his enemies . howard gordon , the episode 's writer , was inspired by various cases of insomnia . during the first season , chris carter had written a similar themed episode , but stopped working on it when he became " unhappy " with the result . plot in new york city , dr. saul grissom finds a fire outside his apartment . when firefighters arrive , they find no fire or any related damage , but discover grissom 's lifeless body . mulder anonymously receives a tape cassette of grissom 's 911 call . he tries to take the case , only to learn that another fbi agent , alex krycek , has opened it first . deciding to leave krycek out of the loop , mulder calls scully ( gillian anderson ) and asks her to conduct grissom 's autopsy . mulder then heads to grissom 's clinic in stamford , connecticut , where he is confronted by an angered krycek . the two travel back to quantico to see scully , who says that grissom 's body showed no signs of a fire , but yet seems to have biologically believed it was burning . meanwhile , in a brooklyn apartment , vietnam veteran henry willig is approached by a fellow ex - marine , augustus cole . suddenly a group of wounded vietnamese appear and gun him down . examining his corpse , mulder and krycek find a scar on his neck and realize he was in the special forces stationed in vietnam in 1970 , and one of only two survivors , the other being cole . they head to the hospital in new jersey where they discover that cole was discharged , despite the fact that his doctor does not remember doing so . mulder meets the mysterious " x " , who gives him information on a secret military project that grissom performed where he eradicated the need for sleep through lobotomy . x provides him with the name of salvatore matola , a squad member who was mistakenly reported as killed in action . a man matching cole 's description robs a drug store . mulder and krycek arrive , but not before two gunshots are heard from the room where cole is believed to be . it appears that the two officers in the room with him shot each other . cole escapes . mulder believes that cole 's years of sleeplessness have provided him with illusionary abilities . mulder and krycek meet with matola soon afterwards , who says that he has not slept in twenty - four years , due to the experiment . he reveals that there was another doctor who was part of the squad , dr. girardi , and that he was the one who actually performed the . mulder and krycek head to the subway station , where dr. girardi is expected to arrive for grissom 's funeral . mulder sees cole there , and cole seems to shoot girardi , but this is shown to be in mulder 's head . in reality , cole has captured girardi and holds him hostage , about to show him a similar fate as his other victims . by searching surveillance footage , they track his location and find girardi wounded . mulder finds cole , who is ready to kill himself . krycek , believing cole is holding a gun instead of the bible he is actually holding , shoots him , and cole dies of his wounds . mulder and scully find both of their files on the case missing . krycek reports to the smoking man and others , telling them that the dissolution of the x - files and the separation of mulder and scully has been ineffective , and their determination is only stronger . he also notes that scully is a bigger problem than they anticipated . production writer howard gordon was initially inspired to write this episode based on insomnia he was suffering at the time . gordon , who wrote many episodes with alex gansa in season one made his solo writing debut with this episode . originally chris carter had written a script for the first season , which shared the same theme as " sleepless . " the original conceit for carter 's episode was " what makes the perfect soldier ? " he also liked the twist on sleep , noting that " sleep is where demons are released in our dreams . " he explained that the characters in " sleepless " were haunted by their memories in real life because they were not able to sleep . carter sees this episode as one of his favorites . this episode marked the first appearance of nicholas lea as alex krycek . carter had much interest in krycek , because he replaced dana scully as mulder 's new partner . lea had previously appeared as a different character in the first season episode , " gender bender . " bowman , who had directed " gender bender , " thought that lea " was a [ ... ] strong choice for a fresh - out - of - quantico fbi agent . " when creating him , the writers always had in mind that he would be a recurring character , while they agreed if the character did not work they would kill him off . " sleepless " marked the first on screen appearance of steven williams as fox mulder 's new source , " x. " the character was originally intended to be a woman , and an actress was cast in the role , but after shooting her first scene the role was recast with williams , an actor who had previous experience with writers glen morgan and james wong . natalija nogulich , the actor who originally earned the role , was replaced because the writing staff felt she was not able to create the " right chemistry " between her co - stars . reception " sleepless " earned a nielsen household rating of 8 . 6 , with a 15 share . it was viewed by 8 . 2 million households in the united states alone . stephen mark was nominated for a primetime emmy award in 1995 in the category " outstanding individual achievement in editing for a series — single camera production " , but did not win . chris carter enjoyed the episode , saying " i really love that show . it 's a great idea , well executed . we had a good cast ; tony todd was wonderful " and saying it was " beautifully directed by rob bowman . entertainment weekly rated " sleepless " with a b + , considering that tony todd 's performance " elevates a just - good story into a great one . " john keegan critical myth gave the episode 7 out of 10 , saying it was best remembered for its introduction of alex krycek . the web site further stated that the episode was decent and was a " fairly standard exploration " for the early season episodes . dave golder from sfx named the episode one of the " 20 tv sci - fi " due to its introduction of krycek . robert shearman and lars pearson , in their book wanting to believe : a critical guide to the x - files , millennium & the lone gunmen , rated the episode four stars out of five . the two noted that gordon was able to make " the cliche of vietnam war guilt " feel " very personal and even sorrowful . " however , shearman and pearson noted that the revelation of krycek as an enemy was " the biggest shame " in the episode . zack handlen from the a.v. club wrote that , while the episode is " your standard riff " , it is important because it features the on - screen introduction of both krycek and x.