# Light Sensitivity in Bipolar Disorder: A Potential Driver of Variability in Sleep, Mood and Energy

> **NIH NIH R21** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2024 · $245,669

## Abstract

ABSTRACT
Bipolar disorder I (BD1) is characterized by pathological mood swings ranging from mania (e.g., high energy,
minimal sleep) to depression (e.g., low energy, increased/decreased sleep). BD affects ~2% of adults, and is
associated with increased disability and mortality. Disrupted sleep and circadian patterns are a primary feature
of BD. Relative to healthy controls and unipolar depression, BD adults are more likely to have a late
chronotype (reflecting later circadian timing) and have more variability in sleep. We have reported that a late
chronotype and increased variability in sleep are predictive of mood and energy in BD. BD1 may be associated
with increased sensitivity to light. Most studies that examined the suppression of nocturnal melatonin secretion
to light have reported increased sensitivity to light in BD1 versus controls, regardless of mood and medications.
However, melatonin suppression is an indirect measure of light sensitivity, is highly variable, and assessment
is limited to night-time. The post-illumination pupil response (PIPR) is a more direct measure of the sensitivity
of the intrinsically photosensitive retinal ganglion cells (ipRGCs) which signal light levels to brain centers that
modulate mood, sleep and circadian rhythms. Only one study has assessed PIPR in BD and found no
difference from controls, but participants’ eyes were dilated which may have maximized light sensitivity (ceiling
effect), and most assessments were at midday when light may have reduced impact. Given the known impact
of light on sleep, mood and energy, there is an important need to assess PIPR in BD. The objective of this
study is to assess light sensitivity with PIPR in BD (euthymic or depressed) and age and sex-matched healthy
controls and to do so at times when light exposure during the waking period has the greatest impact on the
circadian system: right before and right after the nocturnal sleep episode. We will also examine light sensitivity
(PIPR) as a potential driver of variability in sleep, mood and energy. We will leverage our highly engaged and
well-characterized cohort of BD adults who regularly participate in research (Prechter Study). We will enroll 80
participants for a sample of n=60 after attrition (30 BD1, 30 age and sex-matched healthy controls). We
propose a 3-week protocol with 1 week of sleep monitoring using wrist actigraphy (to determine habitual sleep
timing), one night in the sleep laboratory with PIPR assessed 30 minutes before habitual bedtime and 30
minutes after habitual wake time, followed by 2 weeks of wrist actigraphy and ecological momentary
assessment (EMA) to assess variability in sleep, mood and energy. Aim 1: compare light sensitivity between
BD1 and controls. Aim 2: determine if light sensitivity drives variability in sleep, mood and energy in BD1 and
controls. Exploratory Aim: determine if light sensitivity is associated with seasonality and mood course in the
previous year in BD1 and controls. Results wi...

## Key facts

- **NIH application ID:** 10857775
- **Project number:** 1R21MH136155-01
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Helen Julia Burgess
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $245,669
- **Award type:** 1
- **Project period:** 2024-05-01 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10857775

## Citation

> US National Institutes of Health, RePORTER application 10857775, Light Sensitivity in Bipolar Disorder: A Potential Driver of Variability in Sleep, Mood and Energy (1R21MH136155-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10857775. Licensed CC0.

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