Daytime Light Exposure Crucial for Better Sleep in Parkinson's Disease, confirms study

PD patients often experience circadian rhythm disruptions and sleep difficulties, which can exacerbate their symptoms and decrease their quality of life. Previous studies have highlighted the importance of light exposure in modulating circadian rhythms and improving sleep quality.

The study led by Kenji Obayashi, MD, PhD, investigated the association between light exposure and objective sleep measures in PD patients compared to controls. The study involved 189 PD patients and 1101 community-dwelling older adults as controls, assessing daytime and nighttime light exposure and their impact on sleep efficiency, wake after sleep onset, sleep onset latency, total sleep time, and fragmentation index.

The key findings of the study were:

• PD patients exhibited lower levels of daytime light exposure, with a mean light intensity of 201.1 lux (interquartile range [IQR], 101.2 – 305.7), compared to controls with 337.7 lux (IQR, 165.6 – 719) (P < .001).

• Furthermore, patients with PD had higher nighttime exposure, with light intensities of 2.0 (IQR, 0.5 – 7.8) than controls with 0.7 lux (IQR, 0.1 – 3.3) (P < .001).

• Higher daytime light exposure was significantly associated with better sleep efficiency and shorter wake after sleep onset in PD patients.

• The highest quartile of light exposure to ≥ 1000 lux light during the daytime was associated with an 8% greater sleep efficiency (95% CI, 2.1 – 13.4; P = .008) and a shorter short wake after sleep onset by 36.9 minutes (95% CI, 13.4 – 60.3; P = .002) than the lowest quartile.

• Conversely, higher nighttime light intensity was linked to poorer sleep outcomes in PD patients.

• The highest quartile of mean light intensity had significantly reduced sleep efficiency by 6.8% (95% CI, 1.3 – 12.3; P = .016) and had a longer short wake after sleep onset by 24.1 minutes (95% CI, 1.8 – 46.4; P = .034), longer sleep onset latency by 0.7 minutes (95% CI, 0.3 – 1.0; P < .001), and a greater fragmentation index by -0.3 log units (95% CI, 0.0 – 0.5; P = .006).

The study underscores the importance of optimizing daytime light exposure and minimizing nighttime light exposure for improving sleep quality in PD patients. These findings suggest that interventions targeting light exposure could potentially alleviate sleep disturbances in PD patients, thereby enhancing their overall well-being and quality of life.

Reference:

Obayashi K, Saeki K, Tai Y, et al. Daily light exposure profiles and the association with objective sleep quality in patients with Parkinson's disease: The PHASE study. Sleep. Published online February 8, 2024. doi:10.1093/sleep/zsae036