REARDON, Justice.

 The defendant, Seth Grant, was sentenced to 3 to 9 years in the penitentiary after a Logan County jury found him guilty of aggravated battery and obstructing a police officer in violation of sections 12--4(b)(6) and 31--1 of the Criminal Code of 1961 (Ill.Rev.Stat.1973, ch. 38, pars. 12-- 4(b)(6), 31--1).  The court entered judgment on both verdicts, but only sentenced the defendant for the offense of aggravated battery.

 On December 13, 1974, the defendant was a patron at a tavern known as the 'Watering Place' in the City of Lincoln where he consumed four drinks consisting of whisky and cola during a 2 1/2 hour period. The defendant then witnessed an altercation between another patron and the tavern owner.  The Lincoln police were called to the scene and they forcibly escorted the other patron outside where he continued to resist arrest.  A hostile crowd of approximately forty persons accompanied the police and patron as they exited from the tavern and approached the [p. 127] officers' automobile.  The crowd was cheering for the patron.  Suddenly, the defendant burst through the crowd, and, using a parking meter for leverage, he leaped into the air, striking Officer Raymond Vonderahe twice in the face.

 Thereafter, Officer Michael Yarcho placed the defendant under arrest and forcibly led him to the officers' automobile.  Yarcho testified that the defendant was very upset and that great force was required to place the defendant in the automobile.  Another officer, David Morrow, testified that the defendant was excited, agitated and upset.  Morrow also stated that the defendant had not been involved in the altercation prior to his attack on Vonderahe.

 The defendant was transported to the Logan County jail and placed in a cell.  Approximately one hour after being arrested, one of the jailers discovered the defendant lying on his cot gasping for breath.  Defendant's eyes were fixed and his back formed a rigid reversed arch, typical symptoms of a grand mal convulsive seizure. The defendant was immediately transported to a Lincoln hospital by the Lincoln fire department, and then to a Springfield hospital where the defendant remained until December 23, 1974.

 The record on appeal reflects that the defendant has a complicated legal and medical history.  The defendant suffers from an illness known as psychomotor epilepsy.  This history includes a number of violent attacks on other persons which have varied in severity.  In some, physical assistance from others was required to subdue the defendant.  One, a knife assault in a hospital, was of such violence that a police officer seeking to restrain the defendant was forced to use a weapon.  The affray ended only when the defendant was shot in the pelvis and kidney.  His past history is replete with emotional outbursts and he has been convicted on separate occasions of involuntary manslaughter and aggravated assault.

 On appeal, the defendant alleges: (1) that his sanity was not proved beyond a reasonable doubt; (2) that the court erred in giving the usual insanity instruction when his defense was that he suffered an epileptic seizure at the time the offenses were allegedly committed; (3) that his two convictions are for multiple offenses committed during a single course of conduct; and (4) that the sentence imposed by the court is excessive.

 There was no insanity defense at early common law, although courts often entered judgments of guilt with a recommendation that the King pardon a defendant who committed an offense in self-defense or while of unsound mind. (2 F. Pollock & F. Maitland, The History of English Law 479--480 (2d ed. 1898).) Today in Illinois, all men are presumed sane, yet when the evidence raises a reasonable doubt as to a defendant's sanity at the time an offense is committed, then the affirmative defense of insanity is placed in issue for resolution by the fact-[p. 128] finder.  (People v. Redmond (1974), 59 Ill.2d 328, 320 N.E.2d 321.) Once the defense is raised, the presumption of sanity ceases and the State must establish the defendant's sanity beyond a reasonable doubt.  (People v. Ellis (1976), 39 Ill.App.3d 373, 350 N.E.2d 326.) A reviewing court cannot disturb a jury's finding of sanity unless it is so manifestly against the weight of the evidence as to indicate that the verdict was based on passion or prejudice.  People v. Ford (1968), 39 Ill.2d 318, 235 N.E.2d 576.

 The defendant in the instant case argues that his sanity has not been proved beyond a reasonable doubt. Defendant relies on his testimony that his mind went blank at the 'Watering Place' and that he remembered nothing until he awoke three days later.  He stated that he has had previous blackouts and that he takes medicine for epilepsy. Defendant also relies on Dr. Albert Ludin's testimony that defendant has temporal lobe epilepsy with symptoms described as psychomotor and grand mal seizures.  Dr. Ludin expressed his opinion that, at the time the offenses were committed, defendant was suffering from a psychomotor seizure which prevented his conscious mind from controlling his actions.

 The jury is not required to accept the conclusions of a psychiatrist  (People v. Greenfield (1975), 30 Ill.App.3d 1044, 333 N.E.2d 36), and the weight of the psychiatrist's opinion is to be measured by the reasons given for the conclusion and the factual details supporting it.  (People v. Burress (1971),  1 Ill.App.3d 17, 272 N.E.2d 390.) Here, Dr. Ludin stated that his opinion would be different if the defendant was not telling the truth. Analysis of the record on appeal discloses facts on which the jury could base their opinion that the defendant was being untruthful.

 First, defendant alleges that he cannot remember anything that occurred during the three-day period following his arrest.  The doctor, however, testified that on December 14, 1974, defendant was alert, awake and in contact with reality.  Officer Yarcho also stated that the defendant was alert and not confused when he was arrested.  The defendant also responded in an appropriate manner when questioned about his personal history.  Next, is Officer Yarcho's troubling testimony that defendant's arrest required a great deal of force. Such testimony coincides with Dr. Ludin's statement that a person having a psychomotor seizure exhibits a great deal of strength.  This testimony, however, as the State points out, must be contrasted with Officer Yarcho's later testimony that it took four men to place the defendant in an ambulance at the jail, while he initially took the defendant into custody by himself. Furthermore, Officer Yarcho testified that defendant was much stronger during the jail incident than he was during the arrest. Finally, Officer Yarcho stated that in his opinion the defendant was in possession of his 'complete faculties' and 'normal' at the time of his arrest.  The evidence showing that the defendant had a grand mal seizure at the jail does not necessarily reflect that the defendant [p. 129] also had a psychomotor seizure a short time before. While Dr. Ludin did say that sometimes a grand mal seizure is preceded by a psychomotor seizure, he did not say that this always occurs.

 We accordingly hold that the jury's finding of sanity was not against the manifest weight of the evidence.

 The trial court instructed the jury on the question of the defendant's sanity by giving the following instruction which is taken from the Illinois Pattern Jury Instructions, Criminal, No. 24.01 (1968):
'A person is insane and not criminally responsible for his conduct if at the time of the conduct, as a result of mental disease or mental defect, he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of law.
'Abnormality manifested only by repeated criminal, or otherwise anti-social conduct, is not mental disease or mental defect.' (People's Instruction No. 9.)
 This instruction employs language similar to the language contained in section 6--2 of the Criminal Code of 1961 (Ill.Rev.Stat.1973, ch. 38, par. 6--2). This instruction, however, fails to distinguish behavior by a person lacking '* * * substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of law * * *.' (Ill.Rev.Stat.1973, ch. 38, par. 6--2), from automatic behavior by an individual who possesses the requisite capacity.

 We note that this is a case of first impression in Illinois since no Illinois court has determined that a person's actions during a psychomotor epileptic seizure are the actions of an insane person or merely the involuntary or automatic actions of a sane person. . . .

 The term automatism is defined as the state of a person who, though capable of action, is not conscious of what he is doing. Automatism is not insanity.  (LaFave & Scott, Criminal Law s 44 at 337.) In the language of section 4--1 of our Criminal Code, it is manifested by the performance of involuntary acts that can be of a simple or complex nature.  Clinically, automatism has been identified in a wide variety of physical conditions including: epilepsy, organic brain disease, concussional states following head injuries, drug abuse, hypoglycemia and, less commonly, in some types of schizophrenia and acute emotional disturbance.  (LaFave & Scott, 337.) Psychomotor epileptics not only engage in automatic or fugue-like activity, but they may also suffer convulsive seizures. 2 Cecil-Loeb, Textbook of Medicine, ed.  Beeson & McDermott, 1512--1513 (12th ed., 1967).

 Section 4--1 of our Criminal Code provides:
'A material element of every offense is a voluntary act, which includes an omission to perform a duty which the law imposes on the offender and which he is physically capable of performing.  (Ill.Rev.Stat.1973, ch. 38, par. 4-- 1.)
 While the Illinois Pattern Jury Instructions contain an instruction relating to this statute (IPI Criminal No. 4.14), that instruction was neither requested by the defendant nor read to the jury in this case.  Defense counsel, however, objected to the instructions and verdict forms relating to the insanity defense at the instruction conference and in his post-trial motion.

 Section 4--3(a) of our Criminal Code of 1961 provides:
'A person is not guilty of an offense, other than an offense which involves absolute liability, unless, with respect to each element described by the statute defining the offense, he acts while having one of the mental states described in Sections 4--4 through 4--7.' (Ill.Rev.Stat.1973, ch. 38, par. 4--3(a).)
 Thus, the requisite mental state may include, but is not limited to the following:
'A person is reckless or acts recklessly, when he consciously disregards a substantial and unjustifiable risk that circumstances exist or that a result will follow, described by the statute defining the offense; and such disregard constitutes a gross deviation from the standard of care which a reasonable person would exercise in the situation.  An act performed recklessly is performed wantonly, within the meaning of a statute using the latter term, unless the [p. 131] statute clearly requires another meaning.'  (Section 4--6 of the Code (Ill.Rev.Stat.1973, ch. 38, par. 4--6).)
 These statutes relate to the requisite mental state that the defendant may have had at the time he attacked Officer Vonderahe, a question on which the jury was not instructed.

 Ordinarily, a defendant cannot complain on appeal that an instruction was not given if he failed to tender that instruction at trial, (People v. Tannahill (1976), 38 Ill.App.3d 767, 348 N.E.2d 847,) however, Supreme Court Rule 451(c) states that '* * * substantial defects (in jury instructions) are not waived by failure to make timely objections thereto if the interests of justice require.'  (58 Ill.2d R. 451(c).) See People v. Price (1968), 96 Ill.App.2d 86, 238 N.E.2d 881; People v. Lewis (1976), 37 Ill.App.3d 870, 346 N.E.2d 377.

 One of defense counsel's allegations on appeal is that all of the instructions, considered together, confused the jury on the insanity issue.  As noted earlier, this is a case of first impression in this State and we cannot say that the defendant's failure to tender alternative instructions waived the error here. Accordingly, we hold that the interests of justice require reversal of the defendant's convictions because the jury instructions are substantially defective in that they do not contain an instruction on the defense of involuntary conduct.  We note that courts in other jurisdictions have held that the defendant who introduces evidence of abnormal mental condition, bearing upon the state of mind required for the crime with which he is charged, is entitled to an instruction drawing the jury's attention to that evidence. People v. Henderson (1963), 60 Cal.2d 482, 35 Cal.Rptr. 77, 386 P.2d 677; People v. Conley (1966), 64 Cal.2d 310, 49 Cal.Rptr. 815, 411 P.2d 911; State v. Vigliano (1964), 43 N.J. 44, 202 A.2d 657; 22 ALR 3d 1257--1260.

 We distinguish People v. Espenscheid (1969), 109 Ill.App.2d 107, 249 N.E.2d 866, which held that the trial court properly refused to give IPI Criminal No. 4.14 because there was no evidence tending to prove that the defendant performed an involuntary act.  The entire record on appeal here, especially the testimony of Dr. Ludin, reflects that the defendant suffers from psychomotor epilepsy which is not insanity.  The record reflects that the defendant may have been acting in a state of automatism when he attacked Officer Vonderahe on December 13, 1974. We therefore leave the factual resolution of this question to a jury that is properly instructed as to sections 4--1 and 4--3 through 4--7 of the Code.

 Although a voluntary act is an absolute requirement for criminal liability under section 4--1 of our Code (Ill.Rev.Stat.1973, ch. 38, par. 4--1), there is no requirement that every act preceding the actual commission of the offense be voluntary.  Thus, the jury may, on remand, [p. 132] determine that the defendant attacked Officer Vonderahe while in a state of automatism, but that he nevertheless committed an offense for which he is criminally responsible if he had prior notice of his susceptibility to engage in violent involuntary conduct brought on by drinking alcoholic beverages or by some other conscious causal behavior. LaFave & Scott, 181, 337--338.

 We are not troubled by the decision of the British House of Lords affirming a murder conviction in which the trial judge refused to instruct on the defense of automatism despite the presence of evidence tending to establish that the defendant was suffering a psychomotor epileptic seizure at the time the offense was committed.  (Bratty v. Attorney-General for Northern Ireland (1961), 3 All E.R. 535.) Lord Denning's opinion in Bratty states that implementation of the automatism defense, apart from the defense of insanity, is a policy matter that should be reserved for courts and not medical experts.  Lord Denning himself felt that any mental disorder manifesting itself in a form of violence that is prone to recur is a disease of the mind.  He stated that it is the sort of disease requiring detention rather than an unqualified acquittal.

 As noted by LaFave & Scott in their treatise on criminal law:
'If, as just noted, the insanity defense has been utilized as if it 'superceded' a no-mental-state defense for those who might pose a continuing danger because of their mental illness, it might logically be asked whether there has developed a comparable relationship between the insanity defense and the no-voluntary-act automatism defense. That is, is there here as well pressure to 'make the insanity defense the exclusive avenue for bringing subjective evidence into the trial,' to the end that those who did not act voluntarily might be committed if there is some chance that they are still dangerous?
'The few American cases in this area are not particularly helpful in this regard, although they do reflect that what has been described herein as automatism has sometimes been instead labelled insanity, perhaps for the reason suggested above.'  LaFave & Scott, 338--339.

 In Illinois, we have a generally well-reasoned and modern Criminal Code.  (Ill.Rev.Stat.1973, ch. 38, par. 1--1 Et seq.) This Code provides for the affirmative defense of insanity and requires that every offense be the result of a voluntary act.  Our legislature has provided that a person found not guilty of an offense by reason of insanity can be committed to a mental health facility for treatment, although no such provision applies to an alleged offender who commits an involuntary act.  (Section 5--2--4 of the Unified Code of Corrections (Ill.Rev.Stat.1973, ch. 38, par. 1005--2--4)).  These provisions are rational and constitute policy responses to a compelling need by a legislature empowered to act.

 [p. 133] On remand, the defendant will again run the risk of being convicted for the offenses of aggravated battery or obstructing a police officer if the jury finds that he was not insane when he attacked Officer Vonderahe and that he either consciously committed the offense or recklessly brought about his alleged psychomotor epileptic seizure and its accompanying state of automatism.  As some commentators have suggested, the jury plays an important role when the defense is raised:
'* * * automatism as a result of psychomotor seizures should be (a) valid criminal defense.  The dearth of cases employing this defense suggests that the problem is one of proof.  If one is sane immediately prior to and after the unlawful act is committed it is difficult to establish that a particular violent act occurred as a result of a psychomotor seizure.'  (Barrow & Fabing, Epilepsy and the Law (1956), 92--93.)
 If the jury finds that the defendant was sane but not responsible for the attack on Officer Vonderahe, then he cannot be committed for the offenses.  We find this course to be mandated by our legislature which only provided for the commitment of persons who are criminally insane.  Ill.Rev.Stat.1973, ch. 38, par. 1005--2--4.

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 For the reasons stated herein, we reverse the defendant's convictions for aggravated battery and obstructing a police officer, and we remand the case to the Circuit Court of Logan County for a new trial.

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 REVERSED AND REMANDED WITH DIRECTIONS.