Morning melatonin elevation was linked to worse subjective well-being in elite female football players during a training camp.
Evidence
This one-week field assessment followed 22 elite female athletes with actimetry, sleep diaries, well-being ratings, and hourly salivary melatonin self-sampling around sleep and wake times.
Caveat
The study was small, limited to one national squad and one camp week, and reports associations rather than tested circadian interventions.
Simplified
Melatonin production is the gold-standard marker of the physiological "biological night". Assessing it in athletes outside the laboratory enables individualized circadian interventions. This study quantified morning misalignment in elite athletes and examined its association with subjective well-being. Twenty-two elite female athletes (mean age = 26.8 ± 4.3 years) from the same national squad were monitored during a one-week training camp with standardized meal, training and sleep opportunities. Athletes wore actimetry devices to measure sleep and light exposure and completed daily sleep diaries with well-being ratings. On one day, salivary melatonin was self-sampled hourly from four hours before habitual sleep onset to one hour after, and again at wake time and one hour after waking. A longer phase angle between melatonin onset and sleep onset was associated with longer total sleep duration, whereas being an evening chronotype and sharing a room with a dissimilar chronotype were both independently associated with shorter total sleep duration. Elevated melatonin one hour after waking, indicative of morning , was associated with lower subjective well-being. These findings demonstrate that real-life circadian timing influences both sleep and well-being in elite athletes and support the value of individualized circadian-informed strategies to optimize health and recovery.
Key numbers
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Percentage of Athletes Experiencing Misalignment
Athletes waking during biological night based on melatonin levels.
7.37 h
Total Sleep Time in Mixed Chronotype Rooms
Average sleep time for athletes sharing rooms with mixed chronotypes.
5.93 h
Total Sleep Time in Same Chronotype Rooms
Average sleep time for athletes sharing rooms with the same chronotype.
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Circadian Biology