Do Seasonal Changes Affect the Hours of Sleep we need?
Image: ‘Sleeping’ by Daniel Foster is licensed under CC BY-NC 2.0
Most people can agree that our energy levels feel different in the wintertime. However, naturally occurring differences in melatonin provide a biological backing to how our bodies react, sleep-wise, in the winter season versus summer. There is likely a reason why you’re feeling particularly tired on a rainy December afternoon compared to during a sunny August day.
Melatonin – the sleep hormone
Melatonin is a hormone naturally released to induce sleep at appropriate times of the day. A study observing people working typical 5-day workdays reveals that melatonin levels shift between the seasons. These decreased levels are likely linked to the shorter, darker days in winter, which encourages the body to feel more tired earlier in the day.
Is this necessarily a bad thing? One study focusing on adolescents found that they slept fewer hours in the springtime than in winter, and the researchers took the stance of preferring to encourage longer sleep cycles year-round.
An issue is that both abnormal light levels and decreased temperature interact to create a situation in which we require more hours of sleep. For a majority of people, however, workload and standardised corporate schedules mean that adjusting sleep routines to the darker season is unfeasible, explaining why certain demographics, such as younger people who may be in school or university, appear to be more susceptible to seasonal changes.
What is seasonal affective disorder (SAD)?
SAD - also known as winter depression - is a mood disorder that brings about low moods and depression, particularly in the winter season. It has long since been argued that disordered sleep could lie at the heart of depression for some people. Several studies, from those monitoring eye movement in REM to EEG readings, implicate abnormalities in sleep during the winter season, which could contribute to irregular moods.
Currently, the leading explanation is the phase-shift hypothesis, which is the basis for most standardised SAD treatment; those with SAD benefit from manipulating melatonin levels at particular times of day to allow for more regular melatonin and, subsequently, sleep patterns. We cannot ignore the significance of mental health conditions arising from seasonal sleep disruptions.
Adjusting our sleep
Optimal sleep, in regards to both quality and quantity, is imperative year-round and has implications for mental health disorders such as SAD.
Sufficient, quality sleep has reliably been linked to better cognitive functioning, especially in regards to memory, as sleep facilitates better functioning of synaptic connections between neurons or brain cells - these connections’ strength allows for a memory ‘pattern’ to be activated upon we remember something. Being sleep-deprived for even a short period has been found to be significantly detrimental to memory mechanisms, which is definitely not ideal for upcoming exam periods.
Crucially, we must take particular care in the winter to adjust our sleep schedules by sleeping earlier and rising when necessary, despite the weather and climate. As difficult as it may be for students, optimal sleep does appear to be achieved in a quiet, dark environment, avoidant of disruption and blue light. So, this winter, make it a habit to sleep earlier, for longer, without doom-scrolling on Instagram right before bed.