Where Does the Confidence in Getting Good Sleep Despite Drinking Coffee Come From?

There is a common belief that coffee interferes with a good night's sleep. However, some individuals confidently claim that drinking coffee does not affect their sleep. How can this phenomenon be understood from a neurological perspective?

 

Firstly, the awakened brain secretes a neurotransmitter called adenosine. Adenosine accumulates continuously and binds with adenosine receptors distributed throughout the body, inhibiting physical activity. This is a fundamental principle whereby a fatigued body recuperates through sleep. However, adenosine receptors cannot distinguish between caffeine and adenosine because their molecular structures are similar. When caffeine binds to adenosine receptors, it triggers alertness instead of sleep suppression.

 

If despite getting sufficient sleep, concentration is difficult during the day, feelings of fatigue persist, and there's a constant craving for coffee, it's worth considering whether sleep quality is compromised.

 

To maintain sleep, caffeine in the body needs to be metabolized. The half-life of caffeine metabolism is approximately five hours, and for sleep to occur, caffeine concentration should drop to around 50mg. Therefore, consuming coffee with a caffeine content of around 150-200mg in the late afternoon can lead to a reduction in total sleep time or a decrease in sleep quality for most people.

 

However, caffeine metabolism abilities vary among individuals. According to a 2002 study in Denmark, genetic differences in genes involved in caffeine metabolism can result in varying levels of wakefulness effects for each person. Those with genes that metabolize caffeine quickly experience a rapid disappearance of alertness effects. Therefore, even if coffee is consumed late in the afternoon, rapid caffeine metabolism can lead to a transition to sleep. Additionally, individuals with efficient excretion functions or a high innate presence of adenosine receptors may experience a quick elimination of caffeine from the body, reducing wakefulness effects.

 

Some individuals who claim that drinking coffee does not affect their sleep may have a high caffeine intake, or in cases where coffee is consumed just before bedtime, some adenosine receptors may already be bound to caffeine. This can result in a decrease in deep sleep, an increase in shallow sleep, and a deterioration in sleep quality.

 

If despite getting sufficient sleep, concentration is difficult during the day, feelings of fatigue persist, and there's a constant craving for coffee, it's worth considering whether sleep quality is compromised. If this condition persists, it may lead to insomnia and circadian rhythm disorders, and in the long term, immune system suppression and the development of conditions such as depression. Therefore, it is crucial to regulate coffee consumption regularly. However, abrupt discontinuation of coffee can lead to side effects such as headaches and impaired concentration, so establishing a rule of consuming coffee only in the morning is advisable.