Tired and Wired: Why Athletes Can't Switch Off

You're exhausted, but you can't sleep. Your legs feel heavy and your brain won't stop over-thinking. Your autonomic nervous system is stuck in one gear.

What "Tired and Wired" Actually Means for Athletes

Your autonomic nervous system runs on two branches:

  • Sympathetic the "fight-flight-freeze-fawn response": Raises heart rate, mobilizes glucose and sharpens alertness for intervals, game day and deadlines.

  • Parasympathetic the "rest-digest-have sex - recover response": slows heart rate and drives digestion, tissue repair and deep sleep.

Healthy athletes swing between the two.

Tired-and-wired is when sympathetic drive stays switched on while your reserves drain, and the parasympathetic side never gets an opportunity to refuel and regenerate the body.

Training Load Isn't the Only Stressor: Your Total Stress Bill

Your stress response doesn't sort a hard interval session from a hard inbox. It responds to your total load, wherever it comes from – childhood stress, current work stress, deadlines, environmental anxiety.., the list goes on.

A 2022 review in Antioxidants (Matei et al.) puts it bluntly:

  • Exercise is a physiological stressor. How big a stressor is depends on the type and duration of the session and on the person: age, sex and health status.

  • High-intensity work creates oxidative stress that pushes on your autonomic nervous system. The review notes that this downside of exercise has been studied far less than its benefits.

  • Consistent training builds better defences. In animal data cited in the review, trained subjects had lower sympathetic activity and lower oxidative stress.

Training adapts you only when recovery lets it.

Stack these on top of it and the debt you create grows larger:

  • Work pressure and late-night screens

  • Short or broken sleep

  • Under-eating or skipped meals

  • Illness, travel and heat

  • Hormonal shifts of perimenopause or fertility treatments

Signs of Sympathetic Overdrive: The Tired-and-Wired Checklist

Watch for two or more of these together:

  • Resting heart rate creeping up 3–5+ beats above your baseline

  • HRV trending down across several days, not just one bad reading. Be hormone-informed as HRV tends to drift down in the luteal phase. Look at the trends with previous menstrual cycles.

  • 2–3 a.m. wake-ups with a busy brain

  • Flat legs plus a racing mind

  • The 3 p.m. pull toward caffeine or sugar

  • Can't nap even when exhausted

Why these markers matter

A 2025 study of 25 male soccer players found that a slower resting heart rate was linked to:

• Better neuromuscular coordination

• Sleep quality

• Body awareness

It found no link with muscular strength. Your resting heart rate is telling you about readiness and skill execution, not how much you can lift. A study done with women would be great to see!

If your drive and focus swing as much as your legs do, read Dopamine & Performance: The Hormone Connection.

Underfueling and Stress: The RED-S Connection and LEA Note

Low energy availability is a stressor in its own right. When your intake doesn't cover training plus basic physiology, your body reads it as scarcity and keeps the alarm on. This is the core of Relative Energy Deficiency in Sport (RED-S) and Low Energy Availability (LEA).

  • Cortisol stays elevated to keep glucose available

  • Thyroid output and metabolic rate drop

  • Sex hormones are suppressed

  • Sleep, recovery are sacrificed

  • Bone health take a hit as nutrients are diverted to "survival"

Clinically, I see LEA and RED-S far too often. Worse yet, women don’t recognize it for what it is: a busy schedule, no time to eat, food on the go, training and a culturally-rooted desire to be “thin”, “toned”, “lean”.

Under fueling often feels like discipline. If you're chasing weight loss or muscle tone, it can actively block both. Cravings aren't a character flaw either; some are pure physiology, as covered in Late-Night Cravings Aren't Weakness. They're Luteal Biology.

The Bottom Line

Tired-and-wired isn't a toughness problem; it's a regulation problem. Fix the inputs (total stress, fuel and recovery quality) and sleep, performance, hormones and focus follow.

Stuck in the loop? Book an appointment and let's find out what's keeping your system on alert.

References

1. Matei D, Luca C, Onu I, Matei P, Iordan DA, Buculei I. Effects of exercise training on the autonomic nervous system with a focus on anti-inflammatory and antioxidants effects. Antioxidants (Basel). 2022;11(2):350. doi:10.3390/antiox11020350

2. Tekin RT, Kudas S, Buran MM, Cabuk S, Akbasli O, Uludag V, Yosmaoglu HB. The relationship between resting heart rate variability and sportive performance, sleep and body awareness in soccer players. BMC Sports Sci Med Rehabil. 2025;17(1):58. PMID: 40128856. doi:10.1186/s13102-025-01093-7