Effect of extremely low frequency electromagnetic field exposure on sleep quality in high voltage substations.

Abstract

This study aims to investigate the effect of extremely low frequency electromagnetic fields exposure on sleep quality in high voltage substations (132, 230 and 400 KV) in Kerman city and the suburbs. For this purpose, the electric field intensity and magnetic flux density were measured in different parts of substations, and then the occupational exposure was estimated by averaging electric field intensity and magnetic flux density in a shift work. The cases comprised 67 workers who had been exposed to electromagnetic fields in age range of 24-57 and the controls were 110 persons the age ranged 24-50 years. Sleep quality of both groups was evaluated by the Pittsburgh Sleep Quality Index questionnaire (PSQI). Finally, these data were subjected to statistical analysis. The results indicated that 90.5% of cases and 85.3% of controls had the poor quality sleep according to PSQI (P-value=0.615). Total sleep quality score mean for the case and control groups were 10.22 ± 3.4 and 9.74 ± 3.62 (P-value=0.415) ,respectively. Meantime to fall asleep for cases(35.68 ± 26.25 min) was significantly higher than for controls (28.89 ± 20.18 min) (P-value=0.002). Cases had average sleep duration of 5.49 ± 1.31 hours, which was lower ascompared with control subjects (5.90 ± 1.67hours). Although there was a higher percentage for the case group with poor sleep quality than the control group, but no statistically significant difference was observed.

AI evidence extraction

Main findings

Poor sleep quality by PSQI was reported in 90.5% of exposed workers vs 85.3% of controls (P=0.615), and mean total PSQI scores were 10.22±3.4 vs 9.74±3.62 (P=0.415). Time to fall asleep was higher in exposed workers (35.68±26.25 min) than controls (28.89±20.18 min) (P=0.002). Exposed workers had lower average sleep duration (5.49±1.31 h) than controls (5.90±1.67 h).

Outcomes measured

• Sleep quality (Pittsburgh Sleep Quality Index; PSQI)
• Sleep latency (time to fall asleep)
• Sleep duration

Limitations

• Exposure characterized by measured electric field intensity and magnetic flux density averaged over a shift; specific exposure levels not reported in abstract
• Sleep outcomes assessed by self-report questionnaire (PSQI)
• Case-control design; potential confounding not described in abstract
• Control group age range differs from cases (controls 24–50 vs cases 24–57)

Suggested hubs

• occupational-exposure (0.9)
  Study evaluates ELF EMF exposure among substation workers and compares sleep outcomes with controls.

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    "study_type": "case_control",
    "exposure": {
        "band": "ELF",
        "source": "occupational",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "shift work (averaged exposure over a shift)"
    },
    "population": "Workers in high voltage substations (132, 230, 400 kV) in Kerman city/suburbs and control participants",
    "sample_size": 177,
    "outcomes": [
        "Sleep quality (Pittsburgh Sleep Quality Index; PSQI)",
        "Sleep latency (time to fall asleep)",
        "Sleep duration"
    ],
    "main_findings": "Poor sleep quality by PSQI was reported in 90.5% of exposed workers vs 85.3% of controls (P=0.615), and mean total PSQI scores were 10.22±3.4 vs 9.74±3.62 (P=0.415). Time to fall asleep was higher in exposed workers (35.68±26.25 min) than controls (28.89±20.18 min) (P=0.002). Exposed workers had lower average sleep duration (5.49±1.31 h) than controls (5.90±1.67 h).",
    "effect_direction": "mixed",
    "limitations": [
        "Exposure characterized by measured electric field intensity and magnetic flux density averaged over a shift; specific exposure levels not reported in abstract",
        "Sleep outcomes assessed by self-report questionnaire (PSQI)",
        "Case-control design; potential confounding not described in abstract",
        "Control group age range differs from cases (controls 24–50 vs cases 24–57)"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "extremely low frequency",
        "ELF",
        "electromagnetic fields",
        "high voltage substations",
        "occupational exposure",
        "electric field intensity",
        "magnetic flux density",
        "sleep quality",
        "PSQI",
        "sleep latency",
        "sleep duration"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Study evaluates ELF EMF exposure among substation workers and compares sleep outcomes with controls."
        }
    ]
}

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