Delaying your morning caffeine by 90–120 minutes after you wake may boost your afternoon energy, according to experts like Andrew Huberman, neurobiologist with Standford School of Medicine. Learn three scientific reasons why and ways to easily adjust your coffee timing and prevent energy slumps.
What is a caffeine crash?
In simple terms, a caffeine crash occurs when one is unable to endure afternoon fatigue without another cup of coffee. The energy boost from morning caffeine intake wears off for most people in the early afternoon, causing a slump in motivation and productivity. This so-called caffeine crash compels many to drink coffee in the afternoon to reboot focus and drive.
The story behind the caffeine crash
Caffeine doesn’t create energy in your body. Instead, it hides your fatigue. Here’s how the process works.
It centers around adenosine, a neurochemical naturally found in your body to promote the sleep drive — one's need to sleep. Adenosine levels build up in your brain throughout each day. The longer you stay awake, the more adenosine accumulates. Once you fall asleep, adenosine helps prolong deep sleep, known as non-REM sleep.
Adenosine accomplishes this sleep-promoting effect by binding to receptors in your brain. As adenosine levels increase, it binds with more receptors, triggering reduced brain activity and greater sleepiness.
Adenosine levels naturally decline in the morning, but it is not entirely out of your system when you wake. According to Huberman and Matthew Walker, a University of California-Berkeley professor of Neuroscience and Psychology, it takes around 90–120 minutes after you wake up for adenosine to dissolve so you feel less groggy. That's where caffeine comes in.
How caffeine works
Caffeine blocks adenosine's action in the brain, which is why it helps you feel more alert and less sleepy. Long story short, caffeine does this by forcing adenosine out of the receptors and docking there instead. Coffee is able to do this because its molecular structure is similar to that of adenosine.
As a result, adenosine is left freely lingering in the brain, like people without a chair at a party. As the day wears on, more adenosine amasses, as it does every day.
In the afternoon, when the caffeine begins to wear off, fewer caffeine molecules are bound to the receptors. Leftover and newly accumulated adenosine molecules find those receptors and bind there, returning to their sleep-promoting work — making you feel groggy again. This is your afternoon caffeine crash.
Why wait to caffeinate?
Waiting to caffeinate may allow adenosine to clear so that it does not accumulate in the afternoon and cause a caffeine crash. Some experts argue that coffee later in the morning may also protect natural energy regulation systems that involve cortisol as well as adenosine.
Each day, cortisol levels rise in the morning while adenosine levels fall. This chemical mechanism is coordinated by the circadian rhythm, which manages many biological processes throughout the day. According to Huberman, delaying your morning coffee may help preserve this cycle by supporting “the timing in which the sleepy signals [adenosine] and the more energetic signals [cortisol] are arriving.”
The goal is to align caffeine intake with these natural energy management processes. Preserving the normal cycle of adenosine may reduce afternoon fatigue and protect restorative sleep at night, which supports energy levels the following day. Protecting normal cortisol levels in the morning may boost productivity, mood, and motivation.
Caffeine’s effect on cortisol levels
Cortisol, a vital human hormone, works in a normal 24-hour cycle. When it peaks in the morning, cortisol helps clear out adenosine efficiently after you wake.
Caffeine boosts cortisol levels. As a result, one way to enhance the cortisol peak is to drink coffee shortly after the peak occurs. Chronically high levels of cortisol damage the body, but a robust morning peak is a healthy way to enhance motivation and productivity.
According to scientific literature, it may be best to drink coffee near the end of cortisol's peak rather than before it rises earlier in the morning. The theory is that this delay could lengthen and enhance the morning cortisol rise without disrupting its daily cycle.
Dr. Huberman also recommends sunlight and exercise within the first 90 minutes of waking because both boost a healthy cortisol peak, which helps reduce morning adenosine levels.
Caffeine and blood sugar levels
Studies show that caffeine can increase blood sugar levels in some people. Morning coffee and a sugary breakfast on an empty stomach spikes blood sugar levels quickly, increasing the chance of late morning and afternoon fatigue. Steady blood sugar levels throughout the day, on the other hand, help promote sustained energy and suppressed cravings.
Tips for optimal caffeine intake
Optimizing caffeine intake is a simple and potent way to boost your health and protect your sleep. Consider these tips and strategies for how and when to drink coffee to avert energy slumps.
- For optimal coffee intake, drink 3 cups or less daily. According to many studies, coffee and tea are packed with antioxidants. However, as the research suggests, more than 2–3 cups daily likely cause the side effects to outweigh the benefits.
- Wait 90–120 minutes after waking to drink caffeine, especially after a poor night's sleep. Waiting may reduce the afternoon caffeine crash, jitters, disrupted cortisol cycle, and blood sugar spikes. Delaying caffeine may be especially helpful after insufficient sleep because adenosine levels could be higher than normal and will continue to accumulate throughout the day.
- Drink caffeine after your morning breakfast. Eat a savory, high-protein, and fibrous breakfast before drinking coffee later in the morning. A low-sugar meal before coffee may stave off an afternoon blood sugar crash and reduce caffeine jitters.
- For most people, it's okay to drink caffeine on an empty stomach if early morning is your best time to work out both for a physical and mental performance boost, according to Dr. Huberman.
- Start deferring caffeine incrementally. Postpone caffeine by 15 minutes each morning for a week to tolerate later coffee intake.
- If you can't wait, drink half a cup of coffee first. Then, wait 90–120 minutes and drink the rest of your usual morning intake.
- Stop drinking coffee 10–12 hours before you sleep. For most people, half of your morning coffee still blocks adenosine from binding to its receptors 5–6 hours after you drink it. This is known as caffeine's 'half-life.' After 10–12 hours, 25% is still active, which is caffeine’s 'quarter-life.'
- Cold brew may offer the most robust caffeine and antioxidant content. According to Walker, who wrote the book Why We Sleep, data suggests that the longer you brew coffee beans, the higher the caffeine and antioxidant levels.
- Decaffeinated coffee beans deliver the same health benefits as caffeinated. Drinking decaffeinated coffee offers similar antioxidant levels as caffeinated coffee, says Walker.
The circadian rhythm manages regular daily cycles of adenosine and cortisol levels. Delaying caffeine intake for 90–120 minutes after waking may preserve this natural energy management system and reduce the need for afternoon coffee. As a result, you may feel better in the afternoon and sleep deeper throughout the night.
Delaying your morning caffeine by 90–120 minutes after you wake may dramatically boost your afternoon energy and reduce crashes.
Caffeine doesn't create energy in the body. Instead, it hides fatigue by blocking the neurochemical called adenosine, which reduces brain activity and makes you sleepy.
Each day, the longer you stay awake, the more adenosine levels rise in your brain, helping you enter restorative sleep at night. In the morning, cortisol levels rise, which help decrease adenosine and boost energy and productivity.
When you wait 90–120 minutes after waking up to drink coffee, your caffeine intake may be more coordinated with adenosine and cortisol cycles. Data suggests that this could support natural energy levels throughout the day.
Optimizing caffeine intake may be a simple way to boost health for many people. Easy tips and strategies exist for how and when to drink coffee to protect your energy levels.
- Journal of Sleep Research. Adenosine, caffeine, and sleep–wake regulation: state of the science and perspectives.
- Huberman Lab. Using caffeine to optimize mental & physical performance.
- Psychosomatic Medicine. Caffeine stimulation of cortisol secretion across the waking hours in relation to caffeine intake levels.
- British Journal of Nutrition. Glucose control upon waking is unaffected by hourly sleep fragmentation during the night, but is impaired by morning caffeinated coffee.
- Huberman Lab. Dr. Matthew Walker: the science & practice of perfecting your sleep.