Quick Answer: Your Circadian Rhythm Chart is a 24-hour map of your hormones. Key times include 6:00 a.m. (Cortisol spike/wake up), 2:00 p.m. (The "afternoon slump" dip), 9:00 p.m. (Melatonin secretion starts), and 2:00 a.m. (Deepest sleep). Understanding this chart helps you time your caffeine, exercise, and sleep for maximum energy.
In This Guide
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You aren't lazy because you're tired at 2 p.m. You aren't "wired" because you wake up at 7 a.m. You are just biological.
At Mattress Miracle, we help customers find the right bed, but we also help them understand when to be in it. Your body runs on a strict schedule.
The 24-Hour Timeline
Here is the standard biological clock for an adult who wakes at 7 a.m.:
- 6:45 a.m.: Sharpest blood pressure rise.
- 7:30 a.m.: Melatonin secretion stops.
- 10:00 a.m.: Highest alertness.
- 2:30 p.m.: Best coordination.
- 5:00 p.m.: Greatest cardiovascular efficiency and muscle strength.
- 7:00 p.m.: Highest body temperature.
- 9:00 p.m.: Melatonin secretion starts.
- 2:00 a.m.: Deepest sleep.
- 4:30 a.m.: Lowest body temperature.
The Cortisol Awakening
Between 6 a.m. and 8 a.m., your body releases a surge of cortisol. This is the "get up and go" signal.
If you hit snooze repeatedly, you are fighting this natural surge. If you wake up feeling groggy, it might be because your cortisol spike is delayed (common in "night owls") or because you woke up from Deep Sleep (sleep inertia).
Fix: Get bright light immediately. Sunlight anchors this spike to the correct time.
Why You Crash at 2 p.m.
Notice that "Highest Alertness" is at 10 a.m., but there is a natural dip in the early afternoon. This is evolutionary. It's the "siesta" time.
Your body temperature drops slightly, and your brain signals for rest. Fighting this with caffeine often ruins your sleep 8 hours later. Instead, take a 20-minute power nap or go for a brisk walk to raise body temp back up.
The "Dim Light" Window
At 9:00 p.m., your pineal gland starts pumping melatonin. This is the "Dim Light Melatonin Onset" (DLMO).
If you are blasting blue light (TV/Phone) at 9:30 p.m., you are chemically castrating this process. You are pushing your DLMO back to 11 p.m. or midnight, which is why you can't fall asleep.
The Temperature Trap
Notice that 7:00 p.m. is your highest body temp, and 4:30 a.m. is your lowest. To sleep, your temp must drop. If your mattress retains heat, it prevents this drop. A Cooling Mattress helps your body follow its natural chart downward into deep sleep.
Frequently Asked Questions
Does everyone follow this chart?
No. "Night Owls" might be shifted 2-3 hours later. "Early Birds" might be 2 hours earlier. But the sequence of events (cortisol -> alertness -> dip -> melatonin) is the same for everyone.
Why do heart attacks happen in the morning?
The 6:45 a.m. blood pressure spike puts stress on the heart. This is biologically the most dangerous time of day for cardiovascular events.
Can I shift my chart?
Yes, by controlling light. Bright light in the morning pulls the chart earlier. Bright light at night pushes the chart later. You can shift it by about 1 hour per day.
Why do I wake up at 3 a.m.?
Your sleep pressure is lower, and your cortisol starts to rise gently. If you are stressed, that cortisol rises too fast, waking you up. Also, alcohol wears off around this time, causing a rebound wake-up.
Visit Our Brantford Showroom
Mattress Miracle
441 1/2 West Street, Brantford, ON N3R 3V9
Phone: (519) 770-0001
Hours: Mon-Wed 10-6, Thu-Fri 10-7, Sat 10-5, Sun 12-4
Your biological clock needs help. A comfortable, cooling mattress ensures your body can follow its natural rhythm without interruption.