Explain the effects of caffeine on sleep and alertness.

Caffeine has notable effects on both sleep and alertness. It increases alertness primarily by acting as an adenosine antagonist. Adenosine is a molecule in our body that promotes sleepiness as it builds up during waking hours. By blocking adenosine receptors, caffeine temporarily alleviates the feeling of sleepiness, making us feel more awake 1.

Caffeine also influences alertness through its impact on the sympathetic nervous system, increasing epinephrine (adrenaline) levels. This not only boosts energy and alertness but can also lead to jitteriness if consumed in excess. Caffeine enhances the number and efficacy of dopamine receptors, further amplifying alertness and motivation 2.

However, consuming caffeine too late in the day can disrupt sleep architecture. Even if one can fall asleep after having caffeine, the quality of deep sleep and REM sleep is often compromised, which affects how rested you feel the following day 3.

Overall, caffeine can effectively enhance alertness, but it is crucial to time its consumption appropriately—preferably avoiding it 8 to 12 hours before bedtime—to prevent adverse effects on sleep quality 4.