Sleep duration and caffeine consumption in a French middle-aged working population.
Sleep Medicine. 2005-05-01; 6(3): 247-251
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1. Sleep Med. 2005 May;6(3):247-51. Epub 2005 Jan 24.
Sleep duration and caffeine consumption in a French middle-aged working
Sanchez-Ortuno M(1), Moore N, Taillard J, Valtat C, Leger D, Bioulac B, Philip P.
(1)Clinique du sommeil, Centre Hospitalier Universitaire Pellegrin, 33076
OBJECTIVE/BACKGROUND: To explore the association between sleep duration and daily
caffeine intake in a working population. Caffeine acutely disrupts sleep in the
laboratory, but the inter-relations between sleep and caffeine intake in daily
life are ill-known.
METHODS: Questionnaire and diary based survey of 1498 persons from the GAZEL
cohort of employees of the National Electricity and Gas Company (EDF-GDF) working
in various locations in the Paris and South-West France areas. We analyzed total
sleep time, our primary measure, and time in bed, both by sleep logs. We assessed
daily intake of caffeine, consumption of alcohol and tobacco, use of hypnotics,
and daytime somnolence, all by questionnaire.
RESULTS: Multiple linear regression analysis did not find a significant
relationship between total sleep time and daily caffeine intake less than 8 cups
of coffee per day, after controlling for age, gender, alcohol intake, smoking
status, and use of hypnotics. By contrast, time in bed was reduced as caffeine
intake increased (beta=-0.125; P