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In the News

Psychology In The News: Footballers See The Light

Rosey Gardiner-Earl

4th March 2024

As sports people continue to search for marginal gains to improve their performance, more and more are realising the critical importance of sleep. Proper sleep is vital for recovery, muscle protein synthesis, cognitive function, and injury prevention. This is why top footballers are using what we know about circadian rhythms to optimise their sleep-wake cycles.

Our sleep-wake cycles are controlled by the entrainment of our endogenous pacemakers (the suprachiasmatic nucleus or SCN) with exogenous zeitgebers, such as light. Light detected by the eyes sends signals to the SCN. The SCN then signals to the pineal gland to decrease the production of a hormone called melatonin. Rising melatonin levels in the bloodstream in the evening signal to the body and brain that it's time to prepare for sleep. Melatonin therefore helps to initiate the physiological changes that make us feel sleepy.

However, in today’s modern world, LED TVs, computer monitors, smartphones, and tablet screens expose us to large amounts of blue light. This is a problem because blue light can trick your brain into thinking it is daytime (the largest source of blue light we are exposed to is sunlight). Blue light exposure at night suppresses the production of melatonin. When melatonin is low, it's harder to fall and stay asleep. Poor sleep is detrimental for athletes - it impairs muscle recovery, concentration, reaction time, and decision-making.

Erling Haaland, who plays for Manchester City and the Norwegian national team, is known to wear orange-tinted "blue blocker" glasses in the evening. These special glasses block out blue light wavelengths emitted from screens like smartphones, computers, and LED lights.

By putting on blue light blockers at night, Haaland ensures his eyes don't send ‘wake-up’ signals to his brain before bed. For athletes who often travel across time zones or have night games/events disrupting their schedule, maintaining healthy sleep is a constant battle.

In addition, Wolverhampton Wanderers have revealed an unusual technique they are using this season to keep players alert and awake - wearing specialised "daylight glasses." The Premier League club has gone six games unbeaten across all competitions, and while they won't take full credit, the medical training staff believe these glasses provide marginal gains.

The glasses filter light to mimic natural daylight. Players wear them during breakfast or before evening matches to trick their bodies into feeling like it's earlier in the day. As manager Gary O'Neil explained, "When it gets dark, your body naturally starts to feel like it's time to get ready for bed and it isn't time to get ready for bed here!"

Staying alert is crucial for peak athletic performance. But with more evening games and frequent travel across time zones, players' circadian rhythms can get disrupted. Their melatonin levels drop and drowsiness sets in. The daylight glasses boost melatonin to regulate sleep cycles.

As the Premier League gets more competitive than ever, teams are looking for creative ways to gain an edge. More clubs could follow their lead in ensuring players’ bodies don't think "it's time to get ready for bed" before the final whistle blows.

You can see more about this using the following links:


  1. Explain how melatonin is involved in regulating the sleep-wake cycle. How does light exposure, specifically blue light, impact melatonin production?
  2. What are blue-blocker glasses, and why might footballers choose to wear them in the evenings? Relate your answer to the role of melatonin and circadian rhythms.
  3. Describe the technique used by Wolverhampton involving "daylight glasses." Explain how this might help regulate players' circadian rhythms when they have disrupted schedules from travel or evening matches. Use the key terms entrainment, zeitgebers, and melatonin in your answer.
  4. Beyond their use in sports, what other practical applications could benefit from the use of specialised glasses which alter light exposure? Explain your answer.

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Rosey Gardiner-Earl

Rosey has 15 years of experience teaching Psychology and has worked as both a Subject and Senior Leader in school and large sixth form setting. Rosey is also an experienced A level Psychology examiner.

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