A circadian rhythm is a natural, 24-hour cycle that is governed by light and time cues, and is managed by the hypothalamus. Though we often refer to it in terms of sleep cycles, it actually dictates far more than that–hormone release, digestion, mood, alertness, and body temperature. Disrupting it can actually impair memory, mood, and even immune function. Circadian rhythms decide when we’re hungry, or tired, or alert. Learning how to best work with this rhythm can help you maximize your productivity, function, and help you feel more energized overall.

Circadian rhythms are controlled by the SCN (suprachiasmatic neuron) in the hypothalamus, and is

managed by environmental cues, with the strongest being light. It dictates sleep-wake cycles, hormone secretion (like melatonin and cortisol), core body temperature, and even gene expression in organs like the liver and pancreas. Disruption of these functions has been linked to metabolic imbalances, mood disorders, and cognitive impairment. 

Teenagers naturally have a circadian phase delay, making us naturally inclined to fall asleep later and wake up later. However, with schools starting earlier, this gets interrupted, which can lead to poor cognitive function. When your routine aligns with your circadian rhythm, you’re able to focus better; however, disrupting it through irregular sleep patterns, late-night screen time, or skipping meals can throw your body off.

Irregular circadian rhythms can lead to disorientation–for example, your digestive enzymes peaking while you’re asleep, or your alertness dipping during a test. This happens especially with students, who wake up on weekends much later than on weekdays. Research has shown that circadian misalignment reduces cognitive flexibility and impairs memory consolidation. Routine helps your brain predict when to release certain hormones, which improves memory, reduces stress, and helps you fall asleep, wake up, and function during the day.

Chronobiology–the study of biological rhythms–supports several evidence-based strategies for rhythm alignment. Morning light exposure within 30-60 minutes of waking up–and waking up within the same average 1-hour window on most days–can shift the circadian cycle by suppressing melatonin release. Consuming meals at regular times and avoiding blue light exposure an hour before you go to sleep can encourage melatonin release, which helps you fall asleep and stay asleep. Even consistent physical activity can help realign your circadian rhythm. Small adjustments in sleep timing, meal timing, and activity routines can boost your cognitive function, memory retention, and immune system.