Exploring the Relationship Between Caffeine Consumption, Caffeine Metabolism, and Sleep Behaviours: A Mendelian...

Area of Science:

• Genetics
• Pharmacology
• Sleep Science

Background:

• Observational studies suggest a link between caffeine consumption and disturbed sleep.
• The direct causal relationship between caffeine and sleep patterns requires further investigation using robust methodologies.

Purpose of the Study:

• To investigate the bi-directional causal relationships between caffeine consumption, caffeine metabolism, and various sleep traits.
• To determine if observed associations between caffeine and sleep are direct causal effects.

Main Methods:

• Utilized Mendelian Randomisation (MR) analyses with large-scale genetic data from UK Biobank and other studies.
• Employed univariable and multivariable MR to assess causal effects of caffeine on sleep behaviors (e.g., daytime sleepiness, napping, insomnia, sleep duration) and vice versa.
• Investigated genetic variants for caffeine consumption, metabolism, chronotype, and sleep traits.

Main Results:

• Higher caffeine consumption causally decreased daytime sleepiness.
• Faster caffeine metabolism causally decreased the likelihood of daytime napping.
• Being an evening person was causally associated with decreased caffeine consumption.
• No significant causal relationships were found between caffeine consumption/metabolism and sleep duration or insomnia.
• Effects on sleep were primarily related to daytime alertness rather than night-time sleep characteristics.

Conclusions:

• Caffeine consumption appears to causally influence daytime alertness, reducing sleepiness and napping.
• The study provides evidence for a direct impact of caffeine on alertness, but not significantly on insomnia or sleep duration.
• Further research with larger, diverse samples is needed due to limitations like weak instruments for caffeine metabolism and heterogeneity.