Bright light therapy: Improved sensitivity to its effects on rest- activity rhythms in Alzheimer patients by application of nonparametric methods

Eus J.W. Van Someren, Dick F. Swaab, Christopher C. Colenda, Wayne Cohen, William Vaughn McCall, Peter B. Rosenquist

Research output: Contribution to journalArticle

288 Scopus citations

Abstract

Sleep-wake rhythm disturbances in patients with Alzheimer's disease (AD) make a strong demand on caregivers and are among the most important reasons for institutionalization. Several previous studies reported that the disturbances improve with increased environmental light, which, through the retinohypothalamic tract, activates the suprachiasmatic nucleus (SCN), the biological clock of the brain. The data of recently published positive and negative reports on the effect of bright light on actigraphically assessed rest-activity rhythms in demented elderly were reanalyzed using several statistical procedures. It was demonstrated that the light-induced improvement in coupling of the rest-activity rhythm to the environmental zeitgeber of bright light is better detected using nonparametric procedures. Cosinor, complex demodulation, and Lomb-Scargle periodogram-derived variables are much less sensitive to this effect because of the highly nonsinusoidal waveform of the rest-activity rhythm. Guidelines for analyses of actigraphic data are given to improve the sensitivity to treatment effects in future studies.

Original languageEnglish (US)
Pages (from-to)505-518
Number of pages14
JournalChronobiology International
Volume16
Issue number4
DOIs
StatePublished - Jan 1 1999
Externally publishedYes

Keywords

  • Actigraphy
  • Alzheimer's disease
  • Bright light
  • Circadian rhythm
  • Complex demodulation
  • Cosinor
  • Dementia
  • Lomb-Scargle periodogram
  • Periodogram
  • Sleep
  • Statistical Methodology

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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