Opinion by Judge RAWLINSON; Concurrence by Judge WATFORD.
OPINION
RAWLINSON, Circuit Judge:
Appellant Christopher Osinger (Osinger) challenges his conviction for stalking in violation of 18 U.S.C. § 2261A. Osinger asserts a facial challenge to 18 U.S.C. § 2261A as unconstitutionally vague on its face and as applied to his conduct.
[941]*941Osinger also maintains that the district court’s sentence of 46 months’ imprisonment was unreasonable because his acceptance of responsibility and a sentencing disparity warranted a more lenient sentence. We affirm Osinger’s conviction and sentence.
I. BACKGROUND
Osinger was indicted for engaging in a course of harassing and intimidating conduct in violation of 18 U.S.C. §§ 2261A(2)(A) and 2261(b)(5). The indictment alleged that Osinger sent several threatening and sexually explicit text messages, emails, and photographs of V.B., a former girlfriend, to Y.B., as well as to her co-workers and Mends. The indictment also alleged that Osinger “used the Internet to create a Facebook page in a name close to V.B.’s name” to post “suggestive and explicit photos of V.B.” and “demeaning statements, purportedly made by V.B.
Prior to trial, Osinger sought dismissal of the indictment, asserting that 18 U.S.C. § 2261A(2)(A) was unconstitutionally vague. The district court ruled that 18 U.S.C. § 2261A(2)(A) was not unconstitutionally vague and denied Osinger’s motion to dismiss the indictment.
At trial, V.B. testified that she was introduced to Osinger through a mutual Mend. Osinger subsequently became V.B.’s roommate and they became romantically involved. During their nine-month relationship, V.B. allowed Osinger to take nude photographs of her.
Osinger told V.B. that he had divorced his wife in 2005. V.B. eventually moved out of the apartment she shared with Osinger and ended their relationship when she discovered that Osinger was still married. V.B. did not provide Osinger with her new address because she “didn’t want him to contact [her].” Osinger contacted V.B.’s sister-in-law and told her that he knew where V.B. lived and that “he wanted to be with [V.B.].” According to V.B., Osinger “repossessed cars” and “could easily find addresses ...” After Osinger spoke with V.B.’s sister-in-law, V.B. telephoned Osinger because she “wanted him to stop looking for [her] family or Mends, and [she] wanted to hear what he had to say.”
Osinger later came to V.B.’s new residence in an attempt at reconciliation. Osinger arrived in the “early hours of the morning, like 1, 2 in the morning.” V.B. did not answer when he knocked on her window or door because she “didn’t want to speak to him.” Osinger also “came to [her] work a few times.”
When V.B. eventually agreed to meet with Osinger, he told her that he was getting a divorce. Osinger left copies of divorce papers in V.B.’s mailbox, but V.B. doubted their authenticity because they lacked the signature of Osinger’s wife or “any court stamps.” V.B. informed Osinger that she was not interested in continuing their relationship and moved in with her sister. V.B. did not tell Osinger that she was living with her sister and did not provide him with the address. Nevertheless, Osinger called and texted V.B. and eventually came to her sister’s home. V.B. informed him that she was not interested in reviving their relationship.
After V.B. received an offer for a new position in California, she informed Osinger that she was leaving Illinois. Osinger told her that “he would do anything for [them] to be back together,” and was upset that V.B. left without saying goodbye. V.B. did not provide her California address to Osinger.
Following her relocation to California, V.B. continued to receive text messages from Osinger, including messages that he [942]*942wanted “one last chance.” V.B. contacted Osinger when he stated that he would move to California. V.B. told Osinger “to stop texting [her], to stop calling ...”
V.B. continued to receive text messages from Osinger despite her remonstrations. Considering the content of the messages, V.B. inferred that Osinger had sexually explicit videos of her. V.B. construed the text messages as “a threat.” She subsequently received a telephone call from an ex-boyfriend who informed her that “someone had posted a Facebook page with nude pictures of [V.B.] and horrible content ...” When V.B. viewed the Facebook page, she recognized the photographs as ones that Osinger had taken of her. V.B. feared that her family might see the photographs, as one of her cousins had already accepted the Facebook posting.
V.B. contacted Carlos Enriquez, her supervisor, to assist her in removing the Facebook page. V.B. was “crying hysterically” and “could not believe what [Osinger] had done, and [she] was just shocked.” Enriquez removed the Facebook page and informed V.B. that he had been contacted by another employee who had received “an e-mail through his [company] web e-mail with nude pictures of [V.B.].” V.B. received a telephone call from a former coworker in Chicago that “he had also received an e-mail with nude pictures.”
V.B. eventually reported the incidents to the Torrance Police Department because she “was scared. [She] did not know what else [Osinger] was going to try to do.” V.B. ultimately obtained a restraining order against Osinger.
Enriquez corroborated V.B.’s testimony regarding her emotional state and his assistance in removing the Facebook page. Enriquez stayed with V.B. because she “was really bad, still shaking and kind of ... desperate.” Enriquez also received an email at work “with some pictures and with really bad content ...” Enriquez contacted company headquarters to have the email blocked. When Enriquez informed V.B. about the email, she started to cry and shake.
Jason Roberts, V.B.’s former co-worker in Chicago, testified that he “received some pretty disturbing e-mails” on his corporate account. Roberts informed V.B., who “was very, very disturbed, very upset. ...”
Darek Pawelek, V.B.’s ex-boyfriend, testified that he received a Facebook invite that he thought was from V.B., although the name was spelled differently. When Pawelek informed V.B. of the Facebook page’s content, “[s]he got really upset. She started crying, saying things like [she didn’t] know why he is doing this. Why won’t he leave [her] alone.... ”
The jury found Osinger guilty of stalking in violation of 18 U.S.C. §§ 2261A(2)(A) and 2261(b)(5) as alleged in count one of the indictment.
At sentencing, Osinger objected to the recommendation from the probation officer that a downward departure for acceptance of responsibility was unwarranted. Osinger also asserted that a more lenient sentence was supported by the 27-month sentence of another defendant convicted of violating 18 U.S.C. § 2261A. Osinger requested a six-month prison sentence and twelve months in a halfway house.
The district court calculated a base offense level of 18, an adjusted offense level of 22, and a guidelines range of 46 to 57 months’ imprisonment. The district court rejected Osinger’s request for a downward adjustment premised on acceptance of responsibility. After considering the requisite 18 U.S.C. § 3553(a) factors, the district court sentenced Osinger to 46 months’ imprisonment, at the low end of [943]*943the guidelines range, and three years of supervised release.
Osinger filed a timely notice of appeal.
II. STANDARDS OF REVIEW
“A challenge to the constitutionality of a statute is reviewed de novo." United States v. Berry, 683 F.3d 1015, 1020 (9th Cir.2012) (citation omitted). “We also review de novo when a criminal statute is challenged for vagueness.” Id. (citation omitted).
“We review a sentence for both procedural error and substantive reasonableness .... ” United States v. Joseph, 716 F.3d 1273, 1276 (9th Cir.2013) (citation omitted). “We review for clear error the district court’s finding that [Osinger] did not accept responsibility for his crime.” United States v. Ramos-Medina, 706 F.3d 932, 936 (9th Cir.), as amended, cert. denied, — U.S. -, 134 S.Ct. 64, 187 L.Ed.2d 52 (2013) (citation omitted).
III. DISCUSSION
A. Constitutionality of 18 U.S.C. § 2261A1,2
1. Facial Challenge
Osinger contends that the version of 18 U.S.C. § 2261A in effect when he was convicted is facially unconstitutional because it prohibits speech protected by the First Amendment. Osinger also argues that 18 U.S.C. § 2261A(2)(A) is overly broad because it does not define “substantial emotional distress” or “harassment.”3
“In a facial challenge, a statute is unconstitutionally vague if it fails to pro[944]*944vide a person of ordinary intelligence fan-notice of what is prohibited, or is so stan-dardless that it authorizes or encourages seriously discriminatory enforcement... United States v. Harris, 705 F.3d 929, 932 (9th Cir.), as amended, cert. denied, — U.S. -, 133 S.Ct. 1510, 185 L.Ed.2d 561 (2013) (citation and internal quotation marks omitted). Although we have not extensively addressed the First Amendment implications of 18 U.S.C. § 2261A(2)(A), other circuits have rejected similar facial challenges.
For example, in United States v. Petrovic, 701 F.3d 849 (8th Cir.2012), the Eighth Circuit observed that “[a]n overbreadth challenge ... will rarely succeed against a law or regulation that is not specifically addressed to speech or to conduct necessarily associated with speech (such as picketing or demonstrating).” Id. at 856 (citation, alterations, and internal quotation marks omitted). “Section 2261A(2)(A) is directed toward courses of conduct, not speech, and the conduct it proscribes is not necessarily associated with speech.... ” Id. (alteration and internal quotation marks omitted). “Most, if not all, of the statute’s legal applications are to conduct that is not protected by the First Amendment.” Id. (citation and alteration omitted). Additionally, “[t]he rare application of the statute that offends the First Amendment can still be remedied through as-applied litigation.” Id. (citation and internal quotation marks omitted). “Because a substantial number of the statute’s applications will not be unconstitutional, [the Eighth Circuit] deeline[d] to use the strong medicine of overbreadth to invalidate the entire statute.” Id. (citations, alteration, and internal quotation marks omitted).
We agree with the Eighth Circuit’s rationale that, because 18 U.S.C. § 2261A proscribes harassing and intimidating conduct, the statute is not facially invalid under the First Amendment. In particular, 18 U.S.C. § 2261A specifically criminalizes “a course of conduct that ... causes ... substantial emotional distress to [the harassee].” 18 U.S.C. § 2261A(2)(B) (emphasis added). Additionally, 18 U.S.C. § 2266(2) provides that “[t]he term ‘course of conduct’ means a pattern of conduct composed of 2 or more acts, evidencing a continuity of purpose.” Thus, the proscribed acts are tethered to the underlying criminal conduct and not to speech. Moreover, we concur in the Eighth Circuit’s reasoning that, “[b]ecause the statute requires both malicious intent on the part of the defendant and substantial harm to the victim, it is difficult to imagine what constitutionally-protected speech would fall under these statutory prohibitions.” Petrovic, 701 F.3d at 856 (alterations and internal quotation marks omitted); see also United States v. Sayer, No. 12-2489, 748 F.3d 425, 434-36, 2014 WL 1758453, at *7-*8 (1st Cir. May 2, 2014) (rejecting facial challenge to 18 U.S.C. § 2261A(2)(A) on similar grounds).4
Osinger’s argument that 18 U.S.C. § 2261A(2)(A) is unconstitutionally vague because it does not define “harass” or [945]*945“substantial emotional distress” is equally unavailing. “Vague statutes are invalidated for three reasons: (1) to avoid punishing people for behavior that they could not have known was illegal; (2) to avoid subjective enforcement of laws based on arbitrary and discriminatory enforcement by government officers; and (3) to avoid any chilling effect on the exercise of First Amendment freedoms.... ” United States v. Kilbride, 584 F.3d 1240, 1256 (9th Cir.2009) (citation and internal quotation marks omitted). None of these reasons applies here.
Contrary to Osinger’s argument, “harass” and “substantial emotional distress” are not esoteric or complicated terms devoid of common understanding. See, e.g., Adams v. Ford Motor Co., 653 F.3d 299, 307 (3d Cir.2011) (“Black’s Dictionary [784 (9th ed.2009) ] defines harassment as ‘words, conduct, or action (usu. repeated or persistent) that, being directed at a specific person, annoys, alarms, or causes substantial emotional distress in that person and serves no legitimate purpose.... ’ ”); see also Veile v. Martinson, 258 F.3d 1180, 1189 (10th Cir.2001) (describing “substantial emotional distress” to be “understood by persons of common intelligence” to mean “mental distress, mental suffering, or mental anguish, and includes depression, dejection, shame, humiliation, mortification, shock, indignity, embarrassment, grief, anxiety, worry, fright, disappointment, nausea, and nervousness, as well as physical pain” in the context of a state stalking statute) (citations omitted). As the Fourth Circuit observed in United States v. Shrader, 675 F.3d 300 (4th Cir.), cert. denied, — U.S. -, 133 S.Ct. 757, 184 L.Ed.2d 500 (2012), “[w]hatever other definitions one might hypothesize for the meaning of harass or intimidate, there can be little doubt that [the defendant’s] stalking falls within the conduct the statute is intended to proscribe. [The defendant’s] own words evince his intent to cause substantial emotional distress.... In short, we reject [the defendant’s] contention that his stalking convictions must be overturned on vagueness grounds.” Id. at 312 (citation, alteration, footnote reference, and internal quotation marks omitted).
Moreover, 18 U.S.C. § 2261A requires that the defendant act with the intent to harass, intimidate, or cause substantial emotional distress. See 18 U.S.C. § 2261A(2)(A). This scienter requirement, which the jury found had been proven beyond a reasonable doubt, thoroughly undermines Osinger’s contention that he was unable to discern that his harassment of V.B. was proscribed by 18 U.S.C. § 2261A. See United States v. Jae Gab Kim, 449 F.3d 933, 943 (9th Cir.2006), as amended (“[A] scienter requirement may mitigate a law’s vagueness, especially with respect to the adequacy of notice to the complainant that his conduct is proscribed....”) (citation omitted).
Osinger’s threats, creation of a false Fa-cebook page with sexually explicit photographs of V.B., and emails to V.B.’s coworkers and friends containing explicit photographs evinced Osinger’s “intent to ... cause substantial emotional distress ...” 18 U.S.C. § 2261A(2). Thus, Osinger’s unrelenting harassment and intimidation of V.B. was not based on conduct that he “could not have known was illegal.” Kilbride, 584 F.3d at 1256.5
[946]*9462. As-Applied Challenge
Osinger next contends that 18 U.S.C. § 2261A(2)(A) was unconstitutionally applied to his protected speech.
“In an as-applied challenge, a statute is unconstitutionally vague if it fails to put a defendant on notice that his conduct was criminal. For statutes involving criminal sanctions the requirement for clarity is enhanced.” Harris, 705 F.3d at 932 (citations, alterations, and internal quotation marks omitted).
Osinger’s as-applied challenge is unpersuasive given the nature of the implicated speech. “The First Amendment prohibits any law abridging the freedom of speech. However, the Supreme Court has carved out some limited categories of unprotected speech, including obscenity, defamation, fraud, incitement, and speech integral to criminal conduct.” United States v. Meredith, 685 F.3d 814, 819 (9th Cir.), cert. denied, — U.S.-, 133 S.Ct. 563, 184 L.Ed.2d 366 (2012) sub. nom., Giordano v. United States (citations, alteration, and internal quotation marks omitted). “At issue here is the First Amendment exception that allows the government to regulate speech that is integral to criminal conduct....” Id. at 819-20.
In Meredith, we considered whether the defendants’ convictions for advocacy of tax evasion violated the First Amendment. See id. at 817. In addition to selling books explaining how to avoid taxes, the defendants sold a particular type of financial trust “which they claimed was exempt from taxes.... ” Id. at 818. The defendants were charged “with conspiring to defraud the United States by impeding, impairing, obstructing, and defeating the lawful functions of the IRS in the ascertainment, computation, assessment, and collection of federal taxes, in violation of 18 U.S.C. § 371....” Id. In rejecting the defendants’ First Amendment argument, we observed that “in those instances, where speech becomes an integral part of the crime, a First Amendment defense is foreclosed even if the prosecution rests on words alone.” Id. at 820 (citation, alteration, and footnote reference omitted). Because the defendants’ conduct “involved far more than mere advocacy of tax evasion,” the First Amendment was not implicated by the defendants’ “speech integral to criminal conduct.” Id. at 819, 823 (citation omitted).
Although Meredith implicitly undermines Osinger’s argument that he engaged in protected speech, other circuits have explicitly rejected as-applied challenges to 18 U.S.C. § 2261A(2)(A). In Petrovic, the defendant sent the victim text messages stating that he had sexually explicit images [947]*947of her, which the defendant subsequently mailed as postcards to the victim’s family and workplace. See Petrovic, 701 F.3d at 852-53. The defendant also designed a website containing links to the images. See id. at 853. In rejecting the defendant’s as-applied challenge, the Eighth Circuit reasoned that the defendant’s “communications fall outside the First Amendment’s protection” because “[t]he communications for which [the defendant] was convicted under § 2261A(2)(A) were integral to this criminal conduct as they constituted the means of carrying out his extortionate threats....” Id. at 854-55 (citation omitted).
In Shrader, the Fourth Circuit similarly rejected the defendant’s as-applied challenge. In that case, the defendant made a series of harassing phone calls to the victim and her family. See Shrader, 675 F.3d at 304. The Fourth Circuit observed that “[t]he statute contains three important elements. First, the defendant must possess either the intent to kill, injure, harass, or place under surveillance with intent to kill, injure, harass, or intimidate, or cause substantial emotional distress to a person in another State ...” Id. at 309-10 (citation and internal quotation marks omitted). “Second, the defendant must pursue that intention through a course of conduct, defined as a pattern of conduct composed of 2 or more acts, evidencing a continuity of purpose, that makes use of a facility of interstate commerce!.]” Id. at 310 (citations and internal quotation marks omitted). “Finally, the defendant’s conduct must in fact cause substantial emotional distress to the intended victim or place that person in reasonable fear of the death of, or serious bodily injury ...” Id. (citation, alterations, and internal quotation marks omitted). Based on the defendant’s harassing and intimidating conduct, the Fourth Circuit held that “the statute clearly proscribed [the defendant’s] particular conduct in this case. There can be little doubt that [the defendant’s] conduct was harassing and intimidating ...” Id. at 312. As a result, the defendant’s “own words evince his intent to cause substantial emotional distress ...” Id. (citation and internal quotation marks omitted).
We reach a similar conclusion in this case. As described in 18 U.S.C. § 2261A(2)(A), Osinger engaged in a course of conduct “with the intent ... to ... harass, or intimidate, or cause substantial emotional distress to” V.B. V.B. told Osinger repeatedly that she no longer wanted to be contacted by him. Nonetheless, Osinger was unrelenting in his pursuit and harassment of her, including sending threatening text messages. Osinger designed a false Facebook page and sent emails to V.B.’s co-workers containing nude photographs of V.B. Any expressive aspects of Osinger’s speech were not protected under the First Amendment because they were “integral to criminal conduct” in intentionally harassing, intimidating or causing substantial emotional distress to V.B. Meredith, 685 F.3d at 819-20. Pursuant to 18 U.S.C. § 2261A(2)(A), Osinger was on notice that his harassing and intimidating conduct “was criminal.” Harris, 705 F.3d at 932.6
[948]*948In the limited context of 18 U.S.C. § 2261A, Osinger’s speech is not afforded First Amendment protection for the additional reason that it involved sexually explicit publications concerning a private individual. In Petrovic, the Eighth Circuit observed that the victim was “a private individual” and that the defendant’s “communications revealed intensely private information about [the victim].” 701 F.3d at 855 (citation omitted). The Eighth Circuit opined that “the interstate stalking statute is viewpoint neutral. It proscribes stalking and harassing conduct without making the further content discrimination of proscribing only certain forms of that conduct.” Id at 855-56 (citation omitted). “[T]he intimately private facts and photographs revealed by [the defendant] were never in the public domain before [the defendant] began his campaign to humiliate [the victim].” Id at 856. Additionally, “the public has no legitimate interest in the private sexual activities of [the victim] or in the embarrassing facts revealed about her life,” and “the information [the defendant] publicized to the community was highly offensive.” Id (citations omitted). “The communications for which [the defendant] was convicted under § 2261A(2)(A) may be proscribed consistent with the First Amendment. The statute is not unconstitutional as applied to [the defendant].” Id
Osinger’s as-applied challenge is similarly unavailing given his intent to harass and intimidate a private individual by circulating sexually explicit publications that were never in the public domain. Applying the logic of Petrovic and Shrader, we reject Osinger’s as-applied challenge to 18 U.S.C. § 2261A.
B. Osinger’s Sentence
1. Acceptance of Responsibility
Osinger asserts that the district court erred in denying his request for a downward departure premised on acceptance of responsibility. According to Osinger, he intended to plead guilty and proceeded to trial only to preserve his constitutional challenge to 18 U.S.C. § 2261A.
“The Sentencing Guidelines allow district courts to grant a two-level downward adjustment to a defendant who clearly demonstrates acceptance of responsibility for his offense.” Ramos-Medina, 706 F.3d at 940 (citation and internal quotation marks omitted). “The defendant bears the burden of showing that he has accepted responsibility for his actions.” Id (citation omitted).
At trial, Osinger did not simply pursue his First Amendment challenge to 18 U.S.C. § 2261A. Instead, Osinger asserted that his actions were the legal equivalent of “being prosecuted for ripping the label off a mattress.... ” His counsel argued that Osinger was “charged with stalking in the absence of evidence to prove it. There is no history of any violence. There is no history of any threat of violence. There is no history that he ever waited outside her house. There is no [949]*949history that he ever visited her in Los Angeles.” His counsel maintained that “[w]hat the government is asking in this case is that the conviction rest solely on the fact that somebody hurt somebody else’s feelings really, really badly.” Osinger also challenged the jurisdictional basis for the charges by arguing that he thought that he was communicating only with individuals in Chicago where Osinger resided. Osinger asserted that there was no evidence of any threats and that he did not direct the e-mails to V.B., as he sent them only to her co-workers. Osinger argued that there was “[n]o evidence of repetitious conduct and no evidence of malice. A love obsession is not malice.... ” Finally, Osinger maintained that he was not guilty of stalking because he did not contact V.B. after sending the pictures. “On this record, the district court did not clearly err in finding that [Osinger’s] actions were inconsistent with acceptance of responsibili-ty_” Ramos-Medina, 706 F.3d at 942.
In addition to challenging his guilt at trial, Osinger failed to demonstrate the requisite contrition to warrant a downward adjustment for acceptance of responsibility. See United States v. Dhingra, 371 F.3d 557, 568 (9th Cir.2004), as amended (holding that the defendant “did not meet his burden of demonstrating ‘genuine contrition for his acts’”) (citation omitted). Osinger expressed that he “deeply regretted] his conduct.” However, he conveyed his regrets in the context that “as in many breakups things were said and done that people regret. Here, Mr. Osinger said and did things out of anger....” Rather than directly accepting responsibility for his conduct, Osinger intimated that his actions stemmed from V.B.’s refusal to reconcile. Such equivocal expressions of contrition “did not meet [the defendant’s] burden of demonstrating genuine contrition for his acts,” and “it was not clearly erroneous for the district court to deny downward adjustment for acceptance of responsibility.” Dhingra, 371 F.3d at 568 (citation and internal quotation marks omitted).
2. Sentencing Disparity
Finally, Osinger contends that his sentence was unreasonable because another defendant received a more lenient sentence despite engaging in more extensive and intrusive stalking. However, Osinger was not similarly situated to the defendant who received a more lenient sentence after pleading guilty in a different case. See United States v. Espinoza-Baza, 647 F.3d 1182, 1195 (9th Cir.2011) (“It does not matter for the purposes of § 3553(a) that [the defendant] can point to other criminal defendants who may have received lighter sentences under materially different circumstances ....”) (citation, alterations, and internal quotation marks omitted). Osinger’s sentencing disparity argument is undermined by his more extensive criminal history. See id. (observing that the defendant was not similarly situated to other defendants because “[t]here is nothing in the record suggesting that these other defendants had comparable criminal histories”) (citation omitted). Moreover, Osinger’s sentence was at the low end of the guidelines range. See United States v. Green, 592 F.3d 1057, 1072 (9th Cir.2010) (“We have trouble imagining why a sentence within the Guidelines range would create a disparity, since it represents the sentence that most similarly situated defendants are likely to receive.”) (citation and alteration omitted). We hold that Osinger’s sentence was procedurally and substantively reasonable.
IV. CONCLUSION
We adopt the reasoning articulated by the Eighth and Fourth Circuits in Petrovic and Shrader and hold that Osinger’s facial [950]*950and as-applied challenges to 18 U.S.C. § 2261A are unavailing. Osinger’s threatening messages to Y.B. and his sending of sexually explicit photographs to V.B.’s coworkers and friends unquestionably evinced Osinger’s intent to harass and intimidate V.B. and to cause substantial emotional distress. Osinger’s course of conduct was unmistakably proscribed by 18 U.S.C. § 2261A, and any related speech was not afforded First Amendment protection, as it was integral to Osinger’s criminal conduct and involved sexually explicit publications concerning a private individual.
The district court’s sentence of 46 months’ imprisonment, at the low end of the guidelines range, was reasonable because Osinger was not entitled to any downward adjustment premised on acceptance of responsibility or on sentencing disparity.
AFFIRMED.