In seasonal affective disorder, the eyes have it

Pupil response to light differs in people with seasonal affective disorder and is affected by their total exposure to light, researchers will report at Sleep 2014 in Minneapolis.

"We speculate that low light levels in SAD [seasonal affective disorder] trigger downstream changes in mood and behavior, and that the link between light and SAD may be mediated by the PIPR [postillumination pupil response]," Kathryn A. Roecklein, Ph.D., of the University of Pittsburgh and her colleagues wrote in a late-breaker abstract to be presented at the annual meeting of the Associated Professional Sleep Societies.

For their study, the researchers examined postillumination pupil response during summer and winter in 33 people with SAD and 17 controls. One-second light exposures to red light and to blue light were used for testing. Actigraphy was used to measure light exposure in the days before the tests.

In the study subjects with SAD, most of the variance in postillumination pupil response was associated with total photon exposures on the day of testing. In the controls, however, postillumination pupil response was independent of total photon exposures on the day of testing. Blue total photon exposures accounted for the greatest proportion of variance in postillumination pupil response (P = .013) and were predictive of SAD independent of the subject’s gender, time since waking, and whether they were early risers or night owls (P = .013).

The postillumination pupil response was lower in subjects with SAD than in controls (P less than .05), especially among those with SAD who were night owls (P less than .001).

The data, which are the first to link light exposure and the postillumination pupil response in SAD, will be presented in their entirety at the meeting.

The study was funded by a grant from the National Institutes of Health. The authors reported having no financial disclosures.

Pupil response to light differs in people with seasonal affective disorder and is affected by their total exposure to light, researchers will report at Sleep 2014 in Minneapolis.

"We speculate that low light levels in SAD [seasonal affective disorder] trigger downstream changes in mood and behavior, and that the link between light and SAD may be mediated by the PIPR [postillumination pupil response]," Kathryn A. Roecklein, Ph.D., of the University of Pittsburgh and her colleagues wrote in a late-breaker abstract to be presented at the annual meeting of the Associated Professional Sleep Societies.

For their study, the researchers examined postillumination pupil response during summer and winter in 33 people with SAD and 17 controls. One-second light exposures to red light and to blue light were used for testing. Actigraphy was used to measure light exposure in the days before the tests.

In the study subjects with SAD, most of the variance in postillumination pupil response was associated with total photon exposures on the day of testing. In the controls, however, postillumination pupil response was independent of total photon exposures on the day of testing. Blue total photon exposures accounted for the greatest proportion of variance in postillumination pupil response (P = .013) and were predictive of SAD independent of the subject’s gender, time since waking, and whether they were early risers or night owls (P = .013).

The postillumination pupil response was lower in subjects with SAD than in controls (P less than .05), especially among those with SAD who were night owls (P less than .001).

The data, which are the first to link light exposure and the postillumination pupil response in SAD, will be presented in their entirety at the meeting.

The study was funded by a grant from the National Institutes of Health. The authors reported having no financial disclosures.

Pupil response to light differs in people with seasonal affective disorder and is affected by their total exposure to light, researchers will report at Sleep 2014 in Minneapolis.

"We speculate that low light levels in SAD [seasonal affective disorder] trigger downstream changes in mood and behavior, and that the link between light and SAD may be mediated by the PIPR [postillumination pupil response]," Kathryn A. Roecklein, Ph.D., of the University of Pittsburgh and her colleagues wrote in a late-breaker abstract to be presented at the annual meeting of the Associated Professional Sleep Societies.

For their study, the researchers examined postillumination pupil response during summer and winter in 33 people with SAD and 17 controls. One-second light exposures to red light and to blue light were used for testing. Actigraphy was used to measure light exposure in the days before the tests.

In the study subjects with SAD, most of the variance in postillumination pupil response was associated with total photon exposures on the day of testing. In the controls, however, postillumination pupil response was independent of total photon exposures on the day of testing. Blue total photon exposures accounted for the greatest proportion of variance in postillumination pupil response (P = .013) and were predictive of SAD independent of the subject’s gender, time since waking, and whether they were early risers or night owls (P = .013).

The postillumination pupil response was lower in subjects with SAD than in controls (P less than .05), especially among those with SAD who were night owls (P less than .001).

The data, which are the first to link light exposure and the postillumination pupil response in SAD, will be presented in their entirety at the meeting.

The study was funded by a grant from the National Institutes of Health. The authors reported having no financial disclosures.