Energy Hacks: How Sunlight, Sleep Cycles & Circadian Rhythms Affect Fitness

27 December 2025

Hello Ziddis! If you feel lethargic all day, tired and annoyed, overstimulated, inconsistent with your energy and painfully sluggish at times, it is not just about motivation or what you are eating. It could be a circle of bad timing! Didn’t understand? Let us explain. Your body runs on an internal 24-hour clock. This clock likes to control and regulate your energy levels, hunger, performance, recovery and even metabolism. So what happens when you do not provide its timely needs? “Sunlight before screen light” is a trend gone viral to make people realise that they need to start respecting their body’s clock. Light exposure is a strong signal to your body’s clock. Let us understand your body’s cues and how you can help yourself get fitter by giving the right cues to your body.

Circadian Rhythm and Fitness

The circadian rhythm is your body’s clock to regulate the release of hormones, body temperature, alertness, digestion and muscle coordination throughout the day. From a fitness perspective, this rhythm determines:

When you feel energetic without an external stimulus
When your muscles generate maximum force
When your fat oxidation peaks
When recovery and tissue repair are most efficient.

Research published in Chronobiology International shows that strength, flexibility and endurance are usually at peak from late afternoon till early evening. This is also when the core body temperature is increased and neuromuscular coordination peaks.

While working out is great, it is not advised to work out against your natural circadian rhythm. For example, working out late at night, compromising on sleep, or having more screen time can reduce the benefits of your workout.

Sunlight Energy Benefits for Exercise

Sunlight is the most powerful cue to your body and its circadian rhythm. Morning light exposure sends a clear message to your brain that the day has begun, and the tasks are lined up for the body to do. Here is how this helps your body:

Improves your energy and alertness by suppressing melatonin, aka the sleep hormone.
Studies show that morning light exposure can improve hormone regulation and reduce insulin sensitivity.
In 2021, a study published in Sleep Health spoke about how people, when exposed to early daylight, experience better sleep later in the night.
Sunlight helps to enrich our bodies with Vitamin D. Sunlight exposure does just that, but it is beneficial to absorb the sunlight only early in the morning.

Sleep Cycle Hacks for Energy and Workouts

Getting good sleep is not just about how long you have slept but about how deeply you have slept. Here are a few sleep cycle hacks for a consistent flow of energy during workouts

Going to bed and waking up at a consistent time can help you go into REM and deep sleep easily. This can also improve your performance and reaction time.
Keep high-intensity or strength training for morning or late afternoon
Yoga and walking are evening-friendly workouts to feel more relaxed before bedtime.
Dim lights after 8 pm
Avoid screens about 1 hour before bed
Use warm lighting at night.
Heavy meals, especially later at night, can disrupt the sleep cycle, so have a light dinner.

Circadian Rhythm Hacks for Athletes

Athletes and fitness enthusiasts can improve performance by syncing training with their biological clock by:

Training at the same time daily
Having a morning sun exposure workout, like a simple 10-minute walk outdoors.
Using bright lights in the morning, but dim and warm lights in the evening
For those with rotating shifts, you can figure out the best exercises to do in the evening and morning and stick to them.
Fixed meal time can help reset the clock better.

Takeaway

Fitness is not just built in the gym. It is also built into every habit you incorporate. Your body’s internal clock keeps giving you cues for your task. Pay attention to those cues. Have multivitamins if you feel there is a need to push your body beyond the meals and fit foods to replace foods that are not aligned with your healthy habits. Fitness is about syncing your body to the tasks it is meant to do at the time, which is right for it.