Table 2.

Dermatologic conditions associated with NP and SD

Dermatologic disorder (studies)	Prevalence and major SD types	Possible mechanisms of SD	Comments
Atopic dermatitis (Ebata et al., 1999; Kim et al., 2020; Kong et al., 2016; Li et al., 2018; Silverberg et al., 2015; 2018a; 2018b; 2020; Simpson et al., 2016; 2018; Vakharia et al., 2017; Wei et al., 2018; Yano et al., 2013; Yu et al., 2016)	SD in 33%-90% of pts; ↓ SQ, ↓ sleep efficiency*, ↑ SL†, premature sleep awakening; ↑ total scratching time at night, correlates to disease severity; scratching occurs mainly in N1 and N2 stages; ↑ daytime fatigue, ↓ activity of daily living/QoL	CP in 87%-100% of pts; NP and scratching are the most important determinants of SD; epidermal barrier dysfunction can facilitate entry of pruritogens; immune system-mediated release of pruritogenic cytokines; nighttime changes in skin physiology and cytokines can exacerbate atopic inflammation, itch, SD	Severity of AD correlates with SD (↑ total scratching time at night correlates to disease severity); SD and AD may be intricately related (vicious cycle); degree of SD correlates with ↓ QoL; dupilumab treatment decreases SD (Cork et al., 2020; Fargnoli et al., 2019, Tsianakas et al., 2018)
Psoriasis (Hawro et al. 2020; Henry et al., 2017; Jensen et al., 2018; Kimball et al., 2016; Ljossa et al., 2012; Shutty et al., 2013; Smith et al. 2019; Tas et al., 2020; Wu at al., 2008; Zachariae et al., 2012)	SD in 39%-82% of pts; ↓ SQ, ↑ SL, ↓ sleep duration/efficiency, ↑ premature sleep awakening, trouble sleeping due to being too hot and experiencing pain; ↑ daytime somnolence; ↓ QoL	Disorder of thermoregulation and heat loss mechanism leading to ↑ CBT (↓ CBT necessary for sleep initiation); ↓ itch threshold leading to NP; multiple factors affect sleep including pruritus, disease severity, obesity, OSAHS, smoking, comorbid conditions (especially depression), cognitive and somatic arousal	SD showed positive correlation with itch and PASI scores; etanercept (Mrowietz et al., 2015), adalimumab (Strober et al., 2012), and betamethasone dipropionate/calcipotriol (Jalili et al., 2019; Kontochristopoulos et al., 2016) treatments ↑ SQ; psoriasis not a/w SD in 1 study (Stinco et al., 2013)
Hidradenitis suppurativa (Kaaz et al., 2018; Vossen at al., 2017)	SD in 70.4% of pts; ↓ sleep duration, ↑ SL, habitual sleep efficiency; daytime dysfunction	Itch and pain a/w SD; activation of Th17 and Th2 pathways serum level of pruritogenic cytokines; itch and pain have an important impact on insomnia and SQ	Often a/w anxiety, fatigue, depression and stigmatization; pain is a crucial factor in SD
Chronic spontaneous urticaria (Abdel, 2017)	SD in 48.8% of pts; ↑ sleep latency, ↓ sleep duration, ↑ daytime somnolence	Release of histamine, substance P, and CGRP, which ↑ NP and affect SQ	Urticaria severity score – 7 items is proportional to degree of SD; omalizumab treatment may improve SQ (Gimenez et al., 2016)
Infestations (e.g., scabies) (Worth et al., 2012)	SD in 87.5% of pts; ↓ SQ, ↓ sleep duration, ↑ premature awakenings	Scabies mites more active at night; feces (scybala) activate protease activating receptor-2 (pruritic receptor); Th2 immunity against mite results in production of potent pruritogens, such as IL-31	Only cause of NP with acute onset and short duration; SD improves promptly with ivermectin treatment

a/w, associated with; CBT, core body temperature; CGRP, calcitonin gene related peptide; CP, chronic pruritus; IL, interleukin; NP, nocturnal pruritus; OSAHS, obstructive sleep apnea hypopnea syndrome; PASI, psoriasis area severity index; pts, patients; QoL, quality of life; SD, sleep disturbance; SL, sleep latency; SQ, sleep quality; Th, T helper cell

^⁎Sleep efficiency refers to the proportion of time in bed spent sleeping.

^†SL refers to the time between going to be asleep and sleep onset.