How Long Should You Wait Between Drinking Caffeine and Going to Bed?

By Brandon Peters, MD

Caffeine can be one of the great joys of life. If you have difficulty falling asleep, as occurs with insomnia, caffeine in coffee, tea, or soda pop may be the bane of your existence. You may wonder: How long should I wait between my last caffeine and going to bed? Learn how much time should elapse and what symptoms you might experience if you don’t wait long enough before going to sleep.

The Relationship Between Caffeine and Sleep

Good sleep occurs when it is properly timed to take advantage of both the body’s circadian rhythm and sleep drive. For most people, this means spending a prolonged period awake during the day (typically lasting about 16 hours) and attempting to sleep at night. In particular, the sleep drive may be affected by caffeine use.

The sleep drive is understood as the desire for sleep. It builds gradually with wakefulness due to the accumulation in the brain of a chemical called adenosine. Adenosine is a byproduct of metabolism and the longer we stay awake, the more it accumulates and the sleepier we gradually become. Caffeine directly blocks adenosine. This in effect reduces sleepiness and may contribute to difficulty falling or staying asleep after it is consumed. If you are extra sleepy, due to higher adenosine levels from poor quality or inadequate sleep, it may have little to no effect.

How Long to Wait Between Your Last Caffeine and Bedtime?

The million-dollar question is: How long should you wait between your last coffee or soda pop and going to bed? This is likely highly variable and is dependent on your individual levels of adenosine and tendency towards insomnia. For most people, caffeine should be avoided for 4 to 6 hours before bedtime. If you are highly sensitive, you might consider cutting it out after noon (or perhaps entirely).

Since there is some variability in its impacts, you could start by reducing it late and gradually move the deadline earlier as needed. Remember that it can be found in coffee, soda pop, tea, energy drinks, and even chocolate.

Caffeine may affect your sleep, but this may not be the only contributing factor. If you continue to struggle with insomnia, speak with a sleep specialist about other ways to improve your sleep, including participating in a cognitive behavioral therapy for insomnia (CBTI) program.