Circadian Phase Assessments at Home

An estimated 23 million Americans, including adolescents and the elderly, suffer from
circadian rhythm sleep disorders, such as delayed sleep phase disorder, advanced sleep phase
disorder and winter depression. These conditions are characterized by persistent insomnia
and/or excessive daytime sleepiness, impaired performance, reduced well being and lower
quality of life. The negative symptoms result from a misalignment between the timing of
sleep and the internal circadian clock. Clinical research has demonstrated that circadian
rhythm sleep disorders are most effectively diagnosed (differentiated from other causes of
insomnia) and treated if each individual patient's circadian phase is known. The timing of
the master internal circadian clock is most reliably measured from the onset of the
endogenous circadian rhythm of melatonin, a neuroendocrine hormone, as measured in dim light
(dim light melatonin onset, or "DLMO"). However to date the reliable and valid assessment of
the DLMO is limited to the research laboratory setting.

This study is to test a streamlined procedure for the accurate assessment of circadian phase
(DLMO) outside of the laboratory that will provide clinicians and researchers with a novel
diagnostic and research tool. In this way the underlying neurobiological cause of a
patient's insomnia and/or circadian rhythm disorder can more readily be diagnosed and
treated.

Specific Aim 1 is to validate procedures for at-home circadian phase assessment in a sample
of healthy people. Validation will occur by (1) objectively measuring compliance to the
at-home procedures and (2) comparing DLMOs collected at home to DLMOs collected in the
laboratory, in a within-subjects counterbalanced design. Specific Aim 2 is to validate the
same at home procedures in patients with delayed sleep phase disorder. Specific Aim 3 is to
conduct rigorous analyses to inform future users which subject characteristics and light
levels predict (1) compliance to the at home procedures and (2) valid at-home DLMOs.

The results of this 3 year study will have substantial implications for the translation of
basic and clinical research to the community: (1) the diagnosis and treatment of insomnia
and circadian rhythm sleep disorders will be significantly enhanced, thus improving public
health and safety, mood and quality of life, (2) community participation in research will be
improved, particularly in vulnerable and under represented populations, thus increasing
scientific knowledge and (3) research and clinical costs will be substantially reduced.