How well do fixed and free sleep schedules predict the dim light melatonin onset in young healthy subjects

Details

• Personal Author:
  Burgess HJ ; Eastman CI
• Description:
  Introduction: The endogenous melatonin onset in dim light (DLMO) is a commonly used marker of circadian phase, and can be used to determine the time for the administration of light or exogenous melatonin in order to elicit desired circadian phase shifts. In some settings determining the DLMO is not feasible or is prohibitively costly and time-consuming. In this study we examined how accurately the DLMO could be estimated from subjects with free or fixed sleep schedules. Methods: We analyzed baseline data from 100 young healthy subjects who participated in various studies in our lab. Some subjects slept at times of their own choosing ("free sleepers", N=60, mean age 27.3 y) and others slept on a fixed sleep schedule that closely matched their typical sleep schedule ("fixed sleepers", N=40, mean age 24.2 y). Subjects recorded bedtimes and wake times on sleep logs (verified with wrist actigraphy recordings). Each subject then participated in a phase assessment session, where they remained awake but reclined in dim light (<10 lux). Saliva samples were taken every 30 mins and were later assayed to determine the DLMO (20% of maximum method). We analyzed the sleep log data from the 6 days before the phase assessment session. Results: The average (+/- SD) bedtime and wake times for the fixed and free groups were 23:05 +/- 0.8 h, 6:38 +/- 0.7 h and 00:44 +/- 1.2 h, 9:13 +/- 1.4 h respectively, and were significantly later in the free group (both p<0.01). As expected, the within subject variance in bed and wake times was significantly higher in the free sleepers than in the fixed sleepers (p<0.05). However, there was no difference between the groups in the interval from the DLMO to average bedtime (2.3 +/- 1.3 h for fixed sleepers; 2.2 +/- 1.1 for free sleepers). The correlations between bedtime and the DLMO and between wake time and the DLMO were stronger in the free group than the fixed group (free: r=0.65 and r=0.78; fixed: r=0.56 and r=0.47). We derived a regression equation from the relationship between the DLMO and wake time in the free sleepers: DLMO (dec. time) = 0.83 x wake time (dec. time) + 14.90. Using this equation we were able to predict the DLMO to within 1.5 h of when it actually occurred in 96% of subjects from an independent sample of free sleepers (n=26, Martin and Eastman, Chronobiol. Int., 2002). Conclusions: Our results indicate that when measuring circadian phase is too costly or impractical, wake times (verified with wrist actigraphy) in young healthy subjects who sleep at times of their own choosing, can be used to the predict the DLMO. Requiring subjects to maintain a fixed baseline sleep schedule does not appear to improve the ability to predict the DLMO. [Description provided by NIOSH]
• Subjects:
  Circadian Rhythm Men Occupational Health Safety Sleep Sleep Initiation And Maintenance Disorders Women
• Keywords:
  Biological-function Circadian-rhythms Humans Physiological-effects Psychomotor-function Sleep-deprivation Sleep-disorders Statistical-analysis
• ISSN:
  0161-8105
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Illinois ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  26
• NIOSHTIC Number:
  nn:20045660
• Citation:
  Sleep 2003 Jun; 26(Abstract Suppl):A95
• Federal Fiscal Year:
  2003
• Performing Organization:
  Rush University Medical Center, Chicago, Illinois
• Peer Reviewed:
  False
• Start Date:
  19990930
• Source Full Name:
  Sleep
• Supplement:
  Abstract Supplement
• End Date:
  20090430
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:96b07cbf92db6bda90692dcce8ff09d5ff3654db068108c009cf08680256544cb5a4b17f662546081fc8ea63effa329e699e80aa0179d7cfb2bf2921c6da33e3
• Download URL:
  https://stacks.cdc.gov/view/cdc/201005/cdc_201005_DS1.pdf
• File Type:
  [PDF - 37.83 KB ]