Ultramarathon Night Running Techniques: Headlamp Brightness, Nighttime Heart Rate, and Nighttime Fueling Rhythm

Three Core Issues of Nighttime Segments

1. Limited Vision: Depth of field shortens, technical difficulty increases
2. Dropping Body Temperature: Early morning cold can lead to hypothermia
3. Physiological Fatigue: Circadian rhythm low point occurs between 3-5 AM

Headlamp Technique 1: Brightness Distribution

Lumen Segmentation by Use

Dual-Headlamp Strategy

• Primary light: Mounted high on the head, illuminating 10-15m ahead
• Secondary light: Chest-mounted or waist-mounted, illuminating 2-3m at your feet
• Primary + secondary dual light sources eliminate head shadows, making depth perception more stable on descents

Headlamp Technique 2: Color Temperature Selection

Headlamp Technique 3: Batteries and Insulation

• Lithium batteries in 0-5°C environments lose 20-30% of their charge
• Store spare batteries in the inner pocket of your vest (kept warm by body heat)
• Warm the headlamp against your body for 1-2 minutes before changing batteries

Nighttime Heart Rate Regulation

Why Is Nighttime Heart Rate Unreliable?

At night (especially 02:00-05:00):

• Parasympathetic nervous system dominates, resting heart rate can drop 8-12 bpm
• But during exercise, heart rate loses its daytime sensitivity
• At the same RPE, nighttime heart rate may be 10-15 bpm lower

How to Respond

• Switch to RPE instead of heart rate at night
• Don’t speed up just because your heart rate is low
• If your heart rate suddenly spikes, it may be a warning sign of hypoglycemia (not a signal to speed up)

Nighttime Physiological Low Point

Human core body temperature reaches its lowest point at 04:00-05:00, and athletic performance is also at its worst:

Nighttime Nutrition Rhythm

Why Does Nighttime Nutrition Become Harder?

• Appetite decreases (circadian rhythm suppresses appetite)
• Taste changes (sweet foods become cloying, salty foods become more appealing)
• Cold drinks are hard to swallow

Nighttime Menu Adjustments

Caffeine Rhythm

• No caffeine before 00:00: Save it as a weapon for alertness
• First dose at 02:00-03:00: 100-200mg (one strong coffee or 2 gels)
• Second dose at 05:00: Top up with another 100mg
• Avoid taking on an empty stomach: Pair with food to reduce stomach irritation

Nighttime Warmth

For every 5°C drop in temperature, energy expenditure increases by an additional 5-10%:

Key point: Add layers before you feel cold; having hot soup at aid stations adds 5-10°C of perceived warmth.

Nighttime Mental Battle

Coping with Loneliness and Fear

• Do 3-4 simulated night runs before race day (build familiarity)
• Set the next goal: “Get to the 65K checkpoint” instead of “35K to go”
• Think of pleasant things, avoid thoughts like “Will I DNF?”

Coping with Hallucinations

Common hallucinations in ultramarathons (rocks by the trail looking like animals, tree trunks becoming human figures):

• Mostly caused by fatigue and low blood sugar
• Countermeasure: Eat sugar + drink water + take a short 1-2 minute rest
• Don’t scare yourself

Night Running Training Recommendations

• Starting 8 weeks before the race, schedule 2-3 night runs per month
• Simulate race-night gear (headlamp, insulation)
• Do at least one overnight run (actually experience 2-5 AM)

Conclusion

Ultramarathon night running is a technical skill—headlamp, warmth, nutrition, and heart rate regulation are four essential elements, none of which can be overlooked. Training in advance, familiarizing yourself with your gear, and accepting that nighttime performance will inevitably decline are your greatest weapons for surviving the early-morning death zone.

Related Reading

• Ultramarathon Night Running Strategy: Headlamp Selection and Night Running Mental Preparation
• Ultramarathon Night Segments: Mental Coping in the Dark and Headlamp Selection
• Trail Race Night Pacing: The Lonely Battle Under the Headlamp—The Dual Challenge of Pacing and Psychology
• Night Road Race Gear and Safety Strategies: Lighting, Reflective Vests, and Nutrition Adjustments