Effects of caffeine on daytime recovery sleep: A double challenge to the sleep–wake cycle in aging

Carrier, Julie; Paquet, Jean; Fernandez-Bolanos, Marta; Girouard, Laurence; Roy, Joanie; Selmaoui, Brahim; Filipini, Daniel

doi:10.1016/j.sleep.2009.01.001

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Volume 10, Issue 9 , Pages 1016-1024, October 2009

Effects of caffeine on daytime recovery sleep: A double challenge to the sleep–wake cycle in aging

Julie Carrier
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5
- Département de psychologie, Centre de recherche en neuropsychologie et en cognition (CERNEC), Université de Montréal, Montréal, Que., Canada
- Corresponding author. Address: Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5. Tel.: +1 514 338 2222x3124; fax: +1 514 338 2531.
Jean Paquet
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5
Marta Fernandez-Bolanos
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5
- Département de psychologie, Centre de recherche en neuropsychologie et en cognition (CERNEC), Université de Montréal, Montréal, Que., Canada
Laurence Girouard
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5
- Département de psychologie, Centre de recherche en neuropsychologie et en cognition (CERNEC), Université de Montréal, Montréal, Que., Canada
Joanie Roy
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5
- Département de psychologie, Centre de recherche en neuropsychologie et en cognition (CERNEC), Université de Montréal, Montréal, Que., Canada
Brahim Selmaoui
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5
Daniel Filipini
- Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5

Received 13 November 2008; received in revised form 18 December 2008; accepted 5 January 2009.

Abstract

Background and objective

Caffeine is the most widely used stimulant to counteract the effects of sleepiness, but it also produces important detrimental effects on subsequent sleep, especially when sleep is initiated at a time when the biological clock sends a strong waking signal such as during daytime. This study compares the effects of caffeine on daytime recovery sleep in young (20–30 y.) and middle-aged subjects (45–60 y.).

Methods

Subjects participated in both caffeine (200mg) and placebo conditions (double-blind cross-over design), spaced one month apart. For each condition, subjects initially came to the laboratory for a nocturnal sleep episode. Daytime recovery sleep started in the morning after 25h of wakefulness. Subjects were administered either one caffeine (100mg) or placebo capsule three hours before daytime recovery sleep and the remaining dose one hour before daytime recovery sleep.

Results

Middle-aged subjects showed greater decrements of sleep duration and sleep efficiency than young subjects during daytime recovery under placebo compared to nocturnal sleep. Caffeine decreased sleep efficiency, sleep duration, slow-wave sleep (SWS) and REM sleep during daytime recovery sleep similarly in both age groups. Caffeine also reduced N-REM sleep EEG synchronization during daytime recovery sleep (reduced delta, theta, and alpha power, and greater beta power).

Conclusions

The combined influence of age and caffeine made the sleep of middle-aged subjects particularly vulnerable to the circadian waking signal. We propose that lower brain synchronization due to age and caffeine produces greater difficulty in overriding the circadian waking signal during daytime sleep and leads to fragmented sleep. These results have implications for the high proportion of the population using caffeine to cope with night work and jet lag, particularly the middle-aged.

Keywords: Caffeine, Sleep, Sleep deprivation, Aging, Circadian rhythms, Middle-aged, Recovery sleep, Quantitative sleep EEG