These risk factors have been distributed in three distinct categories, i.e., pharmacological triggers, psychiatric and organic predisposing or precipitating conditions, and other factors. Although the causal relationship between these factors and SRED is not confirmed by all the research cited, it was felt that mental health specialists should be warned about the potential need to screen for SRED in patients presenting these factors.
3.1.1. The drug-induced SRED
Regarding the influence of various risk factors in the onset of SRED, there is considerable evidence supporting the impact of certain drugs, such as
the Z-drugs and certain benzodiazepines, all of which share the activation of gamma-aminobutyric acid (GABA) type A receptors. Although the Z-drugs (zolpidem, zaleplon, zopiclone, eszopiclone) target more specifically α-1 subunits of the GABA-A receptors due to their chemical structure (they are imidazopyridines), unlike benzodiazepines or barbiturates, these agents share common pharmacological effects, the risk of abuse and physiological dependence being included [
26,
27]. Zolpidem, several second and third-generation antipsychotic agents (e.g., olanzapine, quetiapine), and antidepressants (e.g., serotonin selective reuptake inhibitors-SSRIs, bupropion) have been associated with sleepwalking or SRED [
28,
29,
30]. Hypnosedative drugs have been associated with various complex sleep behaviors, such as sleep-driving, sleep cooking, SRED, sleep talking, sexsomnia, etc. [
31]. A review that included ten case reports (N=17 patients) on such complex sleep behaviors induced by non-benzodiazepine receptor agonists concluded that zolpidem (N=15), and far more rarely zopiclone (N=1) and zaleplon (N=1) are triggers for sleep eating, sleepwalking with object manipulation, sleep driving/conversation/sex/shopping [
31].
In a study exploring the World Health Organisation (WHO) pharmacovigilance database, out of the 676 drug-associated SRED cases, the most frequent reports involved zolpidem (~36%), sodium oxybate (~27%) and quetiapine (~14%) [
32]. Another study with a similar methodology explored the relationship between lithium carbonate and antipsychotics, on one hand, and the SRED onset, on the other, by extensive research that questioned the WHO pharmacovigilance database (more than 18 million adverse events reported); a total number of 508 SRED cases were found to present a possible involvement of these drugs, out of the 5784 reports of SRED and somnambulism [
33].
In a cross-sectional study (N=1318 patients taking hypnotics), SRED was reported in 8.4% of the cases, especially in young individuals presenting higher Pittsburg Sleep Quality Index (PSQI) scores, who were receiving higher doses of diazepam-equivalent doses of hypnotics [
34]. Subjective adverse effects of hypnotics were present in a significantly higher proportion in patients with SRED; also, taking two or more types of antipsychotics was significantly associated with SRED-type experiences [
34].
In a retrospective study, out of the 125 patients enrolled, diagnosed with depressive disorders, anxiety disorders, adjustment disorders, somatoform disorders, or sleep disorders, who were using hypnosedatives, 19 (~15%) presented complex sleep-related behaviors [
35]. All patients with these behaviors were receiving zolpidem, were younger, more frequently female, took higher doses of Z-drug (over 10 mg/day), and tended not to go to bed immediately after the drug’s ingestion [
35].
According to a literature review (n=40 case reports), SRED was associated with zolpidem administration, especially when doses placed at the higher end or outside the therapeutic interval (≥10 mg/day) were administered [
36]. The relationship between the duration of zolpidem use and the onset of SRED may vary significantly, from one dose to nine years [
36]. The causality of zolpidem administration in the development of SRED was supported by the solving of this condition in all patients who discontinued the administration of the Z-drug [
36]. All patients were unaware of or only partially recalled their SRED episodes [
36]. The effect of zolpidem on increasing phase 3 NREM sleep may be responsible for the onset of sleepwalking or SRED [
37]. In an 8-case series of SRED, zolpidem (10-12.5 mg/day), administered for sleep disorders, was considered the trigger of these nocturnal eating behaviors (1-8 episodes/night, followed by complete amnesia, and their onset was reported 39.8 days after the treatment initiation) [
37]. The discontinuation of zolpidem led to the complete remission of SRED behaviors [
37].
A video report of SRED explored the clinical characteristics of a 53-year-old Caucasian woman with a history of blood hypertension and dyslipidemia, who received 10 mg of zolpidem for five years [
38]. SRED had a frequency of 2-3 episodes/week, and these were accompanied by morning nausea, decreased morning appetite, and fatigue [
38]. From the onset of the SRED behaviors up to the initial visit for clinical evaluation, the patient increased by 6 kg during one year [
38]. The discontinuation of zolpidem led to the disappearance of the SRED [
38].
Sleepwalking, SRED, and sleep-driving were reported as caused by zolpidem use in a 51-year-old African-American woman with a history of mild obstructive sleep apnea (OSA), hypertension, hyperlipidemia, and depression [
39]. Zolpidem immediate release (IR) was initiated for insomnia, and after a few weeks, she presented the onset of the previously mentioned sleep-related behaviors [
39]. Gradual discontinuation of zolpidem was associated with the immediate ceasing of SRED and related disorders [
39]. Two 18-F-fluorodeoxyglucose positron emission tomography (18-F-FDG-PET) recordings were collected two months after zolpidem discontinuation, and 1h after a single-dose rechallenge of zolpidem, with no significant differences between them [
39].
In a case series, five patients were monitored for 11 months for episodes of nocturnal eating behaviors followed by amnesia that had their onset after zolpidem administration [
40]. These patients had comorbid RLS (N=5), OSA (N=3), sleepwalking (N=2), or psychophysiological insomnia (N=1) [
40]. Nocturnal eating behaviors were remitted in all cases once the Z-drug was discontinued [
40]. In a 45-year-old man who presented symptoms of RLS, zolpidem IR (10 mg) was initiated for the control of initial insomnia, the Z-drug being administered twice per week, on average [
41]. After a few weeks, the patient started to walk into the kitchen and ate whatever he could pick approximately two hours after falling asleep, as reported by his family; during these episodes, he was able to cook his meals, and the amount of food ingested was similar to a daytime meal, with complete amnesia [
41]. Nocturnal polysomnography after zolpidem discontinuation revealed a reduced N3 stage, 10-minute sleep latency, and 84.3% sleep efficiency [
41]. After zolpidem discontinuation, SRED remitted and did not re-occur at the 6-month follow-up [
41].
Zolpidem controlled-release (CR) (6.25 mg/day) was administered for insomnia in a 46-year-old woman with a history of depression, hypertension, mild OSA (treated continuous positive airway pressure, CPAP), and hypothyroidism, and it induced amnestic nocturnal eating behaviors starting three weeks after the initiation of the Z-drug [
42]. The SRED episodes began 60-90 minutes after the sleep onset, and they appeared almost every night [
42]. Switching the patient from zolpidem to eszopiclone led to the complete disappearance of the nocturnal eating [
42].
A 45-year-old man with obesity (BMI=35.85 kg/m
2) developed, after ten days of treatment with zolpidem IR 10 mg/day for insomnia, sleepwalking and nocturnal eating behaviors [
43]. More specifically, he walked two kilometers after 2 hours of zolpidem administration, and he was found eating sweets from his own shop [
43]. This episode was followed by complete amnesia of nocturnal eating [
43]. Stopping zolpidem led to the cessation of SRED behaviors [
43].
Zolpidem CR (12.5 mg/day) was considered the trigger for sleep-related complex behaviors (i.e., opening windows, walking, going out of his own house, and SRED behaviors), in a 71-year-old Korean male, who presented complete amnesia for these episodes [
44]. This patient was also diagnosed with RLS and OSA, and he had a low baseline serum level of iron (53 μg/dl, laboratory normal range 60-180 μg/dl) [
44]. Although SRED disappeared once zolpidem was discontinued, RLS symptoms were not impacted; however, these last-mentioned symptoms disappeared after a single i.v. iron injection [
44].
Zolpidem was also associated with the induction of SRED in a 49-year-old man, diagnosed with bipolar disorder, ischemic heart disease, arterial hypertension, obesity, and OSA (initially treated with CPAP, but not tolerated) [
45]. Lamotrigine (200 mg/day), clonazepam (2.5 mg/day), and zolpidem (10 mg/day) were initiated 14 months prior to the SRED diagnosis [
45]. Four months after the zolpidem initiation, the SRED behaviors appeared, followed by complete amnesia, and led to a 20 kg increase in body weight over six months [
45]. The EEG recordings were normal [
45]. The nocturnal eating disappeared after zolpidem discontinuation and was absent at 2- and 5-month follow-up visits [
45].
A 21-year-old woman, diagnosed with an inattentive type of attention-deficit hyperactivity disorder (ADHD) one year before, received 10 mg of zolpidem at bedtime for insomnia [
46]. She did not receive any treatment for ADHD and, after zolpidem initiation, her sleep quality improved [
46]. After two months, she reported a 3 kg weight gain and signs of SRED with complete amnesia [
46]. Zolpidem was tapered to 5 mg, then discontinued and replaced by clonazepam 0.5 mg/day [
46]. After six months, no signs of SRED recurrence could have been detected [
46].
Interestingly, in a report of two SRED cases, extended-release (ER) zolpidem was associated with SRED behaviors, but not the IR formulation [
47]. These patients, a 75-year-old female with RLS, mild OSA, and maintenance-type insomnia, and a 70-year-old white female diagnosed with RLS, complex sleep apnea, and insomnia, received zolpidem ER 12.5 mg at bedtime and developed amnestic SRED behaviors for several consecutive nights [
47]. Discontinuing the zolpidem ER and switching on zolpidem IR led to the remission of these episodes, which persisted at 6 months and 12 months follow-up visits (for the first, and second patient, respectively) [
47].
Also a Z-drug itself, zaleplon is not associated with many reports of SRED behaviors onset. In one such case report, a 49-year-old woman diagnosed with major depression and treated with duloxetine, who did not test positive on a sleep study for any disorders, received zolpidem up to 15 mg/day for insomnia, which determined the onset of SRED behaviors, with a frequency of four episodes/week [
48]. She was switched on zaleplon 10 mg nightly, titrated up to 20 mg, and the SRED re-appeared after 25 months of treatment, with a frequency of 1-4 episodes/week [
48]. NES episodes were also reported by the patient, with preserved, complete recall [
48]. After zaleplon was discontinued, no episodes of nocturnal eating appeared in the next six months [
48].
Triazolam administration was related to the onset of SRED. For example, in a case report, a 48-year-old Japanese woman who was diagnosed with type 2 diabetes mellitus, hypertension, sleep apnea syndrome, depression, and RLS, presented nocturnal eating episodes with partial or complete amnesia, which improved after the dose of triazolam decreased from 0.25 mg to 0.125 mg [
49]. The frequency of abnormal nighttime eating behaviors (that included eating inedible items, such as soap bars) decreased, and this dose adjustment also improved the recollection of her memories of these episodes [
49]. In a case series of 19 adults, triazolam abuse (0.75 mg) was associated with the onset of SRED [
24,
50]. In this case series, nocturnal eating appeared immediately after triazolam abuse, and the discontinuation of this benzodiazepine led to the disappearance of SRED manifestations [
24].
In a 9-year-old male patient with primary clonus dystonia, insomnia, and severe ADHD, initiating clonazepam at 0.5 mg/day led to SRED, which was remitted after benzodiazepine’s discontinuation [
51].
Sodium oxybate is the sodium salt of γ-hydroxybutyrate, which acts as an inhibitory neurotransmitter, and its administration was associated with cases of somnambulism and SRED [
52]. In a case report, the presence of narcolepsy-cataplexy and moderate OSA in a 42-year-old man, undergoing treatment with sodium oxybate 4.5 g/night, titrated up to 8 g/day, the onset of complex activities during sleep was reported two weeks after the maximal dose was reached [
52]. These complex behaviors included driving his car and eating behaviors, but also vomiting and urinating on his own computer, episodes followed by amnesia [
52]. No EEG abnormalities were observed in this patient. The abnormal nocturnal behaviors disappeared after the dose was decreased to 7 g nightly [
52].
Table 2.
Reports included in the review referring to the drug-associated SRED behaviors.
Table 2.
Reports included in the review referring to the drug-associated SRED behaviors.
Reference |
Type of paper |
Main outcomes |
Results and observations |
[28] |
Review (N=148 patients) |
Incidence of drug-induced SRED |
Zolpidem-induced complex sleep behaviors (N=79 patients from case reports and case series, N=69 patients from 1454 patients treated with zolpidem in three observational clinical studies); 88% of cases were found to be probably associated with zolpidem |
[29] |
Case series (N=2 Malay women) |
Evolution of drug-induced SRED |
Quetiapine may induce SRED at various doses, ranging from 50 to 200 mg/day |
[30] |
Review |
Evolution of drug-induced SRED |
Triazolam, lithium, olanzapine, risperidone, zopiclone, zaleplon, and zolpidem ER may be associated with new-onset SRED cases |
[31] |
Review (n=10 reports, N=17 patients) |
Onset of SRED and other sleep-related behaviors |
Zolpidem>zopiclone, zalepon |
[32] |
Retrospective study (N=676 AE reports) |
Drug-associated SRED cases |
Zolpidem (36%)>sodium oxybate (27%)>quetiapine (14%); aripiprazole may be associated with SRED episodes (3.6%); SNRIs antidepressants also determined SRED episodes (2.7% for duloxetine, 2.1% for venlafaxine); psychostimulants (0.4-1.5%) may associate new onset SRED cases |
[33] |
Retrospective study (N=5784 AE reports) |
Drug-associated SRED and somnambulism |
508 SRED cases out of 5784 reports of SRED and somnambulism; quetiapine also was associated with SRED in >53% of these reports |
[34] |
Cross-sectional study (N=1318 patients taking hypnotics) |
Drug-associated SRED |
8.4% presented new-onset SRED, especially young subjects, ↑doses of DZP-equivalent doses, ↑PSQI scores |
[35] |
Retrospective study (n=125 patients) |
Sleep-related behaviors in patients with MDD, anxiety disorders, adjustment disorders, somatoform disorders, or sleep disorders, treated with hypnosedatives |
~15% presented complex sleep-related behaviors, all were treated with zolpidem (over 10 mg/day) |
[36] |
Review (n=40 case reports) |
SRED onset |
Zolpidem (≥10 mg/day) use was associated with SRED |
[37] |
Case series (N=8 patients) |
SRED onset in patients treated with zolpidem |
Zolpidem triggered SRED behaviors (1-8 episodes/night) |
[38] |
Case report (Caucasian woman, 53-year-old) |
SRED onset and evolution |
Zolpidem-induced SRED episodes (2-3 episodes/week) and weight increase (6 kg after 12 months) |
[39] |
Case report (African-American woman, 51-year-old) |
SRED onset and evolution |
Zolpidem IR triggered the onset of sleepwalking, SRED, and sleep-driving |
[40] |
Case series (N=5 patients) |
Nocturnal eating behaviors |
Zolpidem determined SRED and these behaviors disappeared after the drug’s discontinuation |
[41] |
Case report (a 45-year-old man) |
SRED behaviors |
Zolpidem determined night eating and cooking activities |
[42] |
Case report (a 46-year-old woman) |
SRED behaviors |
Zolpidem was administered for insomnia and induced amnestic nocturnal eating behaviors. Switching to eszopiclone led to the complete remission of SRED. |
[43] |
Case report (a 45-year-old man) |
SRED onset and evolution |
Sleepwalking and nocturnal eating behaviors followed by complete amnesia appeared after zolpidem CR was administered; symptoms disappeared after stopping zolpidem use |
[44] |
Case report (a 71-year-old Korean man) |
SRED onset and evolution |
Zolpidem CR triggered SRED and other sleep-related complex behaviors; these symptoms disappeared once zolpidem was stopped |
[45] |
Case report (a 49-year-old man) |
SRED onset and evolution |
Lamotrigine + clonazepam + zolpidem was the combination used to treat this patient with BD; SRED behaviors appeared after the initiation of zolpidem and disappeared when this drug was discontinued |
[46] |
Case report (a 21-year-old woman) |
SRED onset and evolution |
This patient was diagnosed with ADHD and zolpidem was associated with SRED behaviors, which disappeared after this drug’s discontinuation and replacement by clonazepam |
[47] |
Case series (N=2 patients) |
SRED onset and evolution |
Zolpidem ER 12.5 mg/day led to amnestic night-eating behaviors; switching on zolpidem IR led to the remission of these behaviors |
[48] |
Case report (a 49-year-old woman) |
SRED onset and evolution |
This patient was diagnosed with MDD and received treatment with duloxetine and zolpidem up to 15 mg/day; SRED appeared and a switch on zaleplon 10 mg/day was initiated, but SRED and NES episodes persisted; zaleplon discontinuation led to the remission of night eating behaviors |
[49] |
Case report (a 48-year-old Japanese woman) |
SRED onset and evolution |
Triazolam administration led to SRED behaviors; a dose decrease was followed by a reduced frequency of SRED episodes |
[24,50] |
Case series (N=19 patients) |
SRED onset and evolution |
Nocturnal eating appeared immediately after triazolam abuse, and its discontinuation led to symptoms’ remission; amitriptyline (200 mg/day) caused might-eating behaviors that disappeared after drug’s discontinuation |
[51] |
Case report (a 9-year-old boy) |
SRED onset and evolution |
This patient was diagnosed with severe ADHD, clonus dystonia, and insomnia, and clonazepam (0.5 mg/day) was initiated; SRED appeared rapidly after clonazepam administration, and the discontinuation of this drug led to complete SRED remission |
[52] |
Case report (a 42-year-old man) |
SRED onset and evolution |
Sodium oxybate (4.5-8 g/night) initiated for narcolepsy-cataplexy led to the onset of complex activities during sleep, SRED included; these symptoms disappeared after the dose was reduced to 7 g/night |
[53] |
Case report (a 51-year-old woman) |
SRED behaviors in a patient with schizophrenia |
Haloperidol determined RLS, SRED and NES |
[54] |
Case report (a 52-year-old man) |
SRED in a patient with type I BD |
Olanzapine (10 mg/day) added to lithium was responsible for sleepwalking and nocturnal eating episodes with complete amnesia; olanzapine’s discontinuation reversed these episodes |
[55] |
Case report (a 41-year-old Japanese man) |
SRED onset in a patient with MDD |
Aripiprazole (10 mg/day) added to sertraline led to the onset of SRED episodes; reducing the dose to 1.5 mg/day led to the rapid and complete remission of night eating behaviors |
[56] |
Case report (a 48-year-old woman) |
SRED in a patient with rapid-cycling BD |
Quetiapine at bedtime (100 mg) led to the onset of somnambulism and nocturnal eating followed by amnesia |
[57] |
Case series (N=2 patients) |
SRED onset in patients with OSA |
Quetiapine-induced sleepwalking and SRED-like behaviors; quetiapine discontinuation + CPAP therapy led to these symptoms remission |
[58] |
Case report (a 68-year-old man) |
SRED onset in a patient with vascular dementia+ psychotic symptoms |
Risperidone (2 mg/day) determined the onset of nocturnal eating behaviors + complete amnesia; these symptoms disappeared when the dose decreased to 1 mg/day |
[59] |
Case report (a 16-year-old girl) |
SRED onset and evolution |
Risperidone (1 mg/day) led to the onset of SRED behaviors, including dangerous cooking activities; after risperidone was stopped, these eating behaviors disappeared |
[60] |
Case report (a 28-year-old white male) |
SRED onset in a patient with schizoaffective disorder |
Ziprasidone (120 mg/day) induced sleepwalking and SRED; decreasing the dose to 40 mg/day led to the disappearance of SRED; re-challenging with 120 mg/day led to the re-appearance of SRED. |
[61] |
Case report (a 24-year-old woman) |
SRED onset in a patient with MDD |
Fluoxetine (40 mg/day) + trazodone (75 mg/day) + zolpidem (10 mg/day) triggered episodes of nocturnal binge eating with amnesia; switching to mirtazapine (30 mg/day) and clonazepam (0.25 mg/day) led to the transient remission of SRED, but only the complete discontinuation of this antidepressant allowed for the disappearance of SRED |
[62] |
Case report (a 19-year-old woman) |
SRED onset in a patient with anxiety, depressed mood, and suicidal ideation |
Mirtazapine (30 mg/day) led to the development of SRED episodes; these manifestations remitted when the dose was decreased to 15 mg |
[63] |
Case report (a 33-year-old white man) |
SRED in a patient with nicotine use disorder |
Bupropion SR (300 mg/day) induced nocturnal eating episodes, sleepwalking, and telephone use with partial/complete amnesia; these episodes disappeared after the antidepressant’s discontinuation |
[64] |
A case-control study (N=100 patients with RLS and 100 matched controls) |
SRED onset in patients with RLS |
A trend toward the association of dopaminergic agents or hypnotic drugs with SRED in this population was reported (p=0.20) |
[65] |
Expert opinion |
SRED in patients with RLS or PD |
L-dopa/carbidopa and bromocriptine may be associated with new-onset SRED cases |
Antipsychotics, both first-generation and second-generation, have been associated with the onset of SRED. Regarding the first category of antipsychotics, haloperidol determined RLS but also “nocturnal eating/drinking syndrome” (an older term encompassing SRED and NES) in a 51-year-old female patient with schizophrenia [
53]. According to the polysomnography recordings, low levels of sleep efficacy, periodic leg movement, and a correlation between nocturnal eating behaviors and non-REM sleep were observed [
53]. From the atypical antipsychotics class, olanzapine was reported as an inducer of SRED in a 52-year-old man diagnosed with type I bipolar disorder and undergoing maintenance treatment with lithium (750 mg/day) [
54]. Adding olanzapine (10 mg/day) for a hypomanic episode (with a lithium level of 0.6 mEq/l) was followed by sleepwalking and nocturnal eating episodes with complete amnesia [
54]. Olanzapine discontinuation led immediately to the remission of these SRED behaviors [
54].
Aripiprazole may be associated with the onset of SRED behaviors, according to a disproportionality analysis that calculated a 3.6% incidence out of all drug-induced SRED cases (N=676) [
32]. In a case report, a 41-year-old Japanese man diagnosed with depression and undergoing treatment with sertraline (100 mg/day) received aripiprazole (3 mg) as add-on therapy [
55]. After three weeks of combined treatment, episodes of nighttime eating followed by complete amnesia were reported by the patient’s mother [
55]. Reducing the aripiprazole daily dose to 1.5 mg led to the rapid and complete disappearance of SRED-like behaviors [
55].
Quetiapine was the most frequently reported antipsychotic associated with SRED, with over 53% reports in an analysis of the WHO pharmacovigilance database [
33]. The association between the explored drugs and SRED was significant for second-generation antipsychotics and lithium, but not for first-generation antipsychotics [
33]. Quetiapine was considered the trigger for SRED in a 48-year-old woman diagnosed with rapid-cycling bipolar disorder; after two days of quetiapine, 100 mg at bedtime, somnambulism and nocturnal eating followed by amnesia were observed [
56]. The discontinuation of quetiapine led to the remission of her sleep-related disorders [
56]. In another case series, quetiapine-induced sleepwalking and SRED-like behaviors were reported in a 51-year-old African male with obesity and severe sleep apnea (150 mg quetiapine at bedtime, more than a year for depression), and in a 50-year-old African American woman with obesity and mild sleep apnea (200 mg quetiapine, more than a year for depression) [
57]. In both cases, SRED behaviors were remitted after the quetiapine’s discontinuation and CPAP therapy [
57]. Quetiapine was associated with new-onset SRED in a case series (N=2 patients), when administered in doses of 50-200 mg/day [
29].
Risperidone was associated with SRED onset in a 68-year-old man with a psychotic disorder due to vascular dementia [
58]. When the dose of antipsychotic was increased to 2 mg/day, in order to control hallucinations, delusions, and disorganized behaviors that severely impacted his daily functioning, nocturnal eating behaviors appeared (i.e., going to the kitchen, opening the refrigerator, and eating large amounts of food), followed by complete amnesia [
58]. These eating behaviors persisted for two months, during which the patient received 2 mg/day of risperidone, and disappeared rapidly after the dose was decreased to 1 mg/day [
58]. In another case report, risperidone 1 mg/day at bedtime was initiated in a 16-year-old girl for aggressive behaviors such as stealing, property damage, and verbal outbursts; after three days of treatment, approximately two hours after sleep onset, she started to present nocturnal eating behaviors with ingestion of large amounts of food and dangerous eating-related activities, resulting in hurting her finger with a knife while cutting an apple; these episodes appeared 2-3 times/week and led to a significant body weight gain [
59]. This patient did not respond to her mother’s attempts to wake her during the nocturnal episodes and had complete amnesia of her nighttime eating [
59]. Decreased sleep efficiency was observed on polysomnography and the eating episodes disappeared only after risperidone was stopped; at the 1-month and 6-month follow-up visits, she was free of SRED behaviors [
59].
Ziprasidone was considered the trigger of SRED episodes in a 28-year-old white male diagnosed with schizoaffective disorder [
60]. After the dose of ziprasidone was stabilized at 120 mg/day, the patient started to present sleepwalking and SRED for most nights, during the first part of the sleep, followed by complete amnesia in the morning [
60]. He ate only edible foods and engaged in complex behaviors like cooking, but was completely unaware of these episodes, and denied having any other, daytime eating disorder [
60]. The treating physician discontinued the nighttime dose, and preserved only 40 mg in the morning, which led to the disappearance of SRED; a re-challenge of 120 mg/day ziprasidone was initiated later, but the nocturnal eating reappeared [
60].
From the category of
antidepressants, mirtazapine (an inhibitor of the central presynaptic α2-adrenergic receptors) was associated with the onset of SRED in a 24-year-old female patient admitted for depression [
61]. Episodes of nocturnal binge eating with complete amnesia were also reported by this patient while undergoing treatment with fluoxetine (40 mg/day), trazodone (75 mg/day), and zolpidem (10 mg/day), and an increase of 20 kg in 6 months was also reported; switching her on mirtazapine (30 mg/day) and clonazepam (0.25 mg/day) led to the improvement of depressive symptoms and remission of nighttime eating episodes, but after two weeks of treatment these episodes reappeared, with an onset at 1-2 hours after going to bed [
61]. Reducing the dose of mirtazapine to 15 mg/day was not associated with improvements in night eating behaviors, but discontinuation of the antidepressant led to the disappearance of SRED episodes [
61]. A 19-year-old woman diagnosed with SRED and anxiety, depressed mood, and suicidal ideation received treatment with low-dose mirtazapine and was gradually titrated up to 30 mg when she began to develop episodes of nocturnal eating with partial amnesia [
62]. During these episodes, she ate multiple packs of crisps, boxes of biscuits, and other food left near her bed, but also presented abdominal pain and vomiting during the night, and a 4 kg increase in her body weight [
62]. These episodes persisted as long as she received 30 mg of mirtazapine at bedtime but remitted when the dose was lowered to 15 mg [
62].
Antidepressants from the serotonin and norepinephrine reuptake inhibitors class (SNRIs), mainly duloxetine and venlafaxine, were also associated with SRED reports (2.7%, and 2.1%, respectively), in an extensive analysis of the WHO pharmacovigilance database [
32].
In a 33-year-old white man presenting with nicotine use disorder (with a Fagerström score of 8), bupropion sustained-release (SR) 300 mg/day combined with motivational counseling was considered the most appropriate therapeutic intervention [
63]. After 17 days of treatment, nocturnal eating episodes (with high caloric intake), sleepwalking, and telephone use during sleep were reported, with partial or complete amnesia [
63]. After five weeks of treatment with bupropion, this antidepressant was discontinued and the nocturnal eating and somnambulism episodes disappeared rapidly [
63].
Amitriptyline (200 mg/day) caused night-eating behaviors for five years in a 33-year-old woman, even from the beginning of its administration for the control of migraine symptoms; within one week of amitriptyline discontinuation, the night-eating episodes remitted and did not reappear up to the 18-month follow-up [
50]. This patient also presented sleepwalking with complex and violent, non-appetitive episodes, and the RLS diagnosis was supported by the polysomnographic recordings [
50]. Amitriptyline was not the only tricyclic antidepressant involved in the onset of SRED-like episodes, as reported by the same study. An unspecified tricyclic agent probably caused SRED behaviors in a 58-year-old woman diagnosed with depression, without a history of sleepwalking or RLS, and without signs of recurrence after two years of drug discontinuation [
50].
There are also reports that could not significantly correlate the use of
dopaminergic or hypnotic drugs for RLS with the presence of SRED, but support a trend for the first category of drugs (67% vs. 52%, p=0.20) [
64]. The administration of dopamine agonists (l-dopa/carbidopa, bromocriptine) was, however, involved in the onset of abnormal eating behaviors in patients with RLS and Parkinson’s disease [
50,
65]. Although these reports do not specifically mention SRED, at least some of the cases could be related to this pathology.
Psychostimulants may trigger SRED-like behaviors, and (dex)amphetamine, lisdexamphetamine, armodafinil, methylphenidate, modafinil, and phentermine were associated with such abnormal eating behaviors in 0.4-1.5% of the drug-induced SRED cases [
32].
3.1.2. Psychiatric and organic disorders as potential risk factors for SRED
Regarding the correlation between psychiatric disorders or symptoms and SRED, more severe levels of
depression and
dissociation have been reported in patients with nocturnal eating vs. controls [
66]. Between the
substance use disorders, alcohol withdrawal, opiate/cocaine abuse, and cigarette smoking cessation were involved in the onset of SRED [
24,
50].
Both
daytime eating disorders, NES, and other sleep disorders were reported in patients with SRED. In a case series (N=19 patients) alcohol and other substance abuse was detected in 21% of these patients [
24]. In a case series with 19 adults (mean age 40 years), SRED was associated with OSA, more specifically eating during apnea-induced confusional arousals, periodic limb movement + OSA, familial sleepwalking, sleepwalking + periodic limb movement disorder, sleepwalking + irregular sleep/wake pattern disorder, familial RLS, anorexia nervosa with nocturnal bulimia, and amitriptyline treatment for migraines [
50].
Patients presenting other sleep disorders are more predisposed to the onset of SRED [
30]. SRED and nocturnal eating behaviors are frequently detected in relation to RLS, possibly due to the mistreatment with sedative agents [
23]. A review found that OSA, depression, and RLS were the most frequently reported disorders in these patients’ medical history, and new-onset SRED was present even in patients well-treated for these comorbidities [
36].
A survey that took place in a sleep disorder center (N=53 patients presenting RLS) showed that 66% of the responders had frequent night-eating behaviors, and 45% had SRED [
67]. According to a case-control study (N=100 patients with RLS and 100 matched controls), SRED was more frequently associated with RLS than with the control condition (33% vs. 1%) [
64]. Also, patients with both SRED and RLS used more medication and had higher scores on the Maudsley Obsessive-Compulsive Inventory (MOCI) than patients presenting RLS without SRED [
64].
In a cross-sectional study, nocturnal eating episodes were reported in 31% of the 120 patients diagnosed with RLS, but the difference between SRED and NES was not explored [
68]. However, these episodes were more frequently detected in RLS patients than in the general population, indicating the need to carefully analyze the comorbidities of patients with RLS [
68].
Table 3.
Reports included in the review referring to non-pharmacological triggers of SRED behaviors.
Table 3.
Reports included in the review referring to non-pharmacological triggers of SRED behaviors.
Reference |
Type of paper |
Main outcomes |
Results and observations |
[24,66] |
Review + a 5-year study (N=19 participants) |
Risk factors for SRED |
Depression severity, dissociative symptoms, SUDs; daytime eating disorder, NES, other sleep disorders |
[50] |
Case series (N=19 patients) |
Risk factors for SRED (pharmacological and non-pharmacological) |
OSA, PLM, familial sleepwalking, and irregular sleep/wake pattern disorder, familial RLS, anorexia nervosa with nocturnal bulimia, and migraines treated with amitriptyline were associated with SRED and NES behaviors; acute stress derived from worries about the safety of family members or relationships problems may trigger SRED |
[30] |
Narrative review |
Risk factors for SRED |
Other sleep disorders can be considered a risk factor for SRED |
[23] |
Survey-based study (N=130 patients) |
Risk factors for NES and SRED |
RLS is frequently related to SRED, possibly mediated by mistreatment with sedative agents |
[36] |
Review (n=40 case reports) |
Risk factors for SRED |
OSA, MDD, and RLS were the most frequent disorders reported in patients with SRED |
[67] |
Survey-based study (N=53 patients) |
Risk factors for SRED in a group of patients with sleep disorders |
66% of the responders had frequent night-eating behaviors, 45% had SRED |
[64] |
A case-control study (N=100 patients) |
Risk factors for SRED in patients with RLS |
RLS was associated more frequently with SRED than the control group; ↑MOCI scores in patients with both RLS and SRED |
[68] |
Cross-sectional study (N=120 patients) |
SRED and NES in patients with RLS |
SRED or NES were detected more frequently in patients with RLS than in the general population |
[69] |
Case report (a 34-year-old white man) |
SRED onset and evolution |
OSA and SRED can be frequently detected together; OSA may precipitate the onset of SRED |
[70] |
Case series (N=2 patients) |
SRED onset and evolution |
Narcolepsy and OSA may be predisposing factors for SRED; work-related stress, disturbance of the circadian rhythm due to professional tasks, and insufficient time allocated to sleep were reported as risk factors for SRED |
[71] |
Cross-sectional study (N=65 patients) |
SRED in patients with narcolepsy vs. healthy controls |
Narcolepsy and cataplexy were more frequently associated with SRED; ↑severity of depression, in females, and higher scores of bulimia and social insecurity on EDI-2, ↑MOCI scores |
[72] |
A controlled study (N=36 patients) |
SRED vs. sleepwalking profiles |
A personal history of eating problems in childhood and ↑current anorexia scores were reported in patients with SRED/sleepwalking vs. healthy controls |
[73] |
A case series (N=2 patients) |
SRED in patients with PD |
OSA, NES, and REM sleep disorders were present as comorbidities; |
[74] |
Case report (a 56-year-old woman) |
SRED in a patient with PD |
SRED was detected together with PD, OSA, sleepwalking, depression, and REM sleep parasomnia |
OSA and SRED can be detected frequently together, although one of them may be incidentally discovered in a patient diagnosed and treated for the other [
69]. OSA may be caused by weight gain secondary to the SRED, or both conditions can be caused by a single incident (such as a head trauma with nasal and mandibular injury, according to a case report) [
69]. OSA may precipitate the onset of SRED because it interrupts sleep [
69].
Narcolepsy and OSA also may be predisposing factors for the SRED onset [
70]. Patients presenting narcolepsy with cataplexy had a high prevalence of SRED (32%) in a cross-sectional study that compared 65 consecutive adult patients with narcolepsy and a similar number of healthy controls [
71]. Patients with narcolepsy and cataplexy had more frequently an eating-related pathological profile on Eating Disorder Inventory-2 (EDI-2) (80% vs. 46% in healthy controls) [
71]. Also, a higher prevalence of depressed mood was detected in these patients, according to the Beck Depression Inventory (BDI) scores, vs. patients without SRED [
71]. Patients with narcolepsy and SRED were more frequently women, presented higher scores on „bulimic” and „social insecurity” factors on the EDI-2, had higher obsessive-compulsiveness on the Maudsley Obsessive-Compulsive Inventory (MOCI), and were more depressed according to the BDI scores, compared to patients with narcolepsy but without SRED [
71].
Daytime eating disorders were reported in 10% of the SRED patients [
50]. In a previously cited, 5-year study (N=19 participants), SRED was also often accompanied by other dysfunctional behaviors during the night, with only two patients presenting an eating disorder (anorexia nervosa), and almost 50% having another psychiatric diagnosis, such as mood and anxiety disorders [
24]. A personal history of eating problems in childhood and higher current anorexia scores were reported in patients with SRED vs. healthy controls or patients with sleepwalking [
72].
Parkinson’s disease (PD) was considered a possible trigger for SRED behaviors. In two patients with early-onset PD, a 28-year-old male and a 37-year-old male, SRED was confirmed by audio-video polysomnography [
73]. In the first patient, besides SRED, episodes of confusional arousals during N3 sleep were recorded, while in the second case, OSA, NES and REMSBD were present as comorbidities [
73]. Sleep hygiene education and a decrease of pramipexole daily dose to 1.5 mg, together with the introduction of 150 mg levodopa daily led to the disappearance of SRED in the first patient, while in the second patient, the correct treatment of OSA with CPAP and sleep hygiene education were sufficient to cancel the nocturnal eating behaviors [
73]. A 56-year-old woman, with a two-year history of PD (treated consecutively with carbidopa/levodopa, pramipexole, amantadine, and propranolol), was also diagnosed with hypothyroidism (undergoing treatment with levothyroxine), depression (treated with nortriptyline), OSA (but could not tolerate CPAP treatment), sleepwalking, REM sleep parasomnia, and bruxism; SRED was also detected, based on her husband’s reports, without any daytime eating disorder [
74]. SRED in patients with PD has been conceptualized as a comorbidity or an adverse effect of dopaminergic activators. However, pramipexole, which is a dopaminergic activator, was associated with favorable results in patients with SRED [
75].