Sleepy is not always
the same as sleeping well.
Coffee, alcohol and nicotine affect sleep in different ways. Look beyond whether something makes you feel awake or drowsy right now.
Three familiar effects to question.
Caffeine · alertness that can outlast the cup
Caffeine blocks some adenosine signalling and can mask sleepiness. Coffee, tea, energy drinks, cola and chocolate can contain it. Effects last for hours and vary between people.
Alcohol · drowsiness followed by disruption
Alcohol can make you feel sleepy initially, then make sleep lighter and more interrupted. It can also worsen snoring or breathing problems. It is not a reliable sleep aid.
Nicotine · a stimulant, even when the habit feels calming
Nicotine can increase alertness and interfere with sleep. Smoking and nicotine-containing vapes both deliver nicotine. If you want help stopping, a pharmacist or stop-smoking service can advise.
Lee falls asleep quickly after a drink but wakes repeatedly later. Has the drink necessarily improved the night?
Read the explanation
Alcohol can make the first part feel easier while disrupting later sleep. Sleep quality includes what happens after you fall asleep.
Caffeine does not have a universal cut-off.
A late cup can still be active at bedtime. The NHS advises avoiding tea or coffee for at least six hours before bed; some people are affected for longer.
Notice both timing and amount. Choosing an earlier last caffeinated drink is a practical experiment, not a guarantee. Feeling able to fall asleep does not prove caffeine has no effect.