TOPLINE

Higher light exposure at nighttime was associated with higher risk for obesity, hypertension, and dyslipidemia than lower light exposure at nighttime in patients with schizophrenia, a new cross-sectional study showed.

METHODOLOGY

• The Light Exposure and Neurobiology in Schizophrenia (LENS) study included more than 200 adults from Japan diagnosed with schizophrenia (median age, 50 years; 55% men) and assessed the associations between nighttime light exposure and metabolic dysfunction in 2024.
• Light exposure was measured between bedtime and rising time. Patients wore an actigraph on the wrist for 24 hours a day and placed a bedside photometer at their eye level for 7 consecutive days.
• Patient height, weight, BMI, abdominal circumference, and blood pressure were evaluated and blood samples were collected to measure levels of plasma glucose, A1c, triglycerides, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C).
• Metabolic dysfunction was defined according to Japanese guidelines as the presence of obesity (BMI ≥ 25), hypertension (systolic blood pressure ≥ 140 mm Hg, diastolic blood pressure ≥ 90 mm Hg, or use of antihypertensive medication), diabetes (casual plasma glucose levels ≥ 200 mg/dL, A1c levels ≥ 6.5%, or use of antihyperglycemic medication), or dyslipidemia (triglyceride levels ≥ 175 mg/dL, HDL-C levels < 40 mg/dL, LDL-C levels ≥ 140 mg/dL, or use of lipid-lowering medication).
• The analysis was adjusted for age, sex, current smoking status, daytime physical activity, total sleep time, rising time, antipsychotic dose, and antidepressant use.

TAKEAWAY

• Patients with the highest vs lowest quartile of actigraphy-measured nighttime illuminance had significantly higher odds of obesity (adjusted odds ratio [aOR], 4.01; P < .01), hypertension (aOR, 3.38; P < .01), and dyslipidemia (aOR, 2.41; P = .01).
• Increased nighttime illuminance was significantly linked to higher A1c levels (P < .01) but not to diabetes.
• The group with the highest vs lowest quartile of nighttime illuminance had significantly higher body weight (+10.3 kg), abdominal circumference (+8.5 cm), BMI (+3.4), and systolic blood pressure (+10.1 mm Hg; P < .01 for all); higher diastolic blood pressure (+6.0 mm Hg; P = .02); higher levels of A1c (+0.37%; P = .01), triglycerides (+77.0 mg/dL; P = .03), and LDL-C (+13.4 mg/dL; P = .02); and lower levels of HDL-C (-8.5 mg/dL; P = .01).
• Photometry-measured nighttime illuminance was also significantly associated with higher odds of hypertension (aOR, 3.02; 95% CI, 1.25-7.29).

IN PRACTICE

The LENS findings showed that “maintaining darkness during sleep can be a novel clinical therapeutic option for metabolic dysfunction in patients with schizophrenia,” which could lead to increased life expectancy, the investigators wrote.

SOURCE

The study was led by Rina Taniguchi, PhD, Okehazama Hospital, Toyoake, Japan. It was published online on June 29 in Sleep.

LIMITATIONS

The study was limited by its nonrandom sampling, lack of the confirmation of adherence to fasting requirements by the patients, a lack of a specific diet questionnaire for patients with mental health issues, and potential confounders.

DISCLOSURES

The study was funded by Japan Society for the Promotion of Science-KAKENHI and Takeda Science Foundation. Disclosure information for the study investigators is available in the original study publication.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.