Coffee is sold as a rapid remedy for tiredness, but coffee often makes people sleepy. Such a phenomenon is common knowledge in the field of sleep studies and nutrition and is generally linked to the mechanism of caffeine action. In this edition of ‘Everyday Explained,’ HT Lifestyle spoke to Dr Eileen Canday, the head of the department of nutrition and dietetics at Sir H N Reliance Foundation Hospital, Mumbai, to understand the reason behind this.
Adenosine is a metabolic product that is accumulated in the brain throughout the day and serves as a “signal of sleep pressure. If caffeine inhibits these receptors, then the brain does not realise the signal, so the person feels awake, and adenosine continues to accumulate in the brain. Thus, the same amount of caffeine blocks fewer receptors in the brain, and a person becomes sleepy faster.
Dr Canday highlighted the ‘mask and rebound’ effect due to the fact that caffeine provides a person with wakefulness mainly through inhibition of adenosine receptors in the brain .
“Caffeine tolerance, sleep debt and timing, as in the case of regular consumption of much caffeine, the brain becomes tolerant and changes its sensitivity to adenosine,” said Dr Canday.
- Sleep 7-8 hours, as no matter how much coffee you have, sleep debt cannot be paid back. When you lack sleep badly, the levels of adenosine will be so high that it will out-compete caffeine partially, and this makes the effects of caffeine less. In other words, drinking caffeine when very sleep-deprived results in increased fatigue.
