It’s quite common to feel more tired and lethargic as the nights draw in and the days get shorter. But does your body really need more sleep in the winter?
Research suggests that the average adult needs seven hours or more sleep per night, regardless of the season. The exact number of hours required differs for each individual based on their lifestyle, age, gender and more. But there are some factors that may affect how much sleep you need during winter.
Temperature
The human body can adjust to a wide range of ambient temperatures, but there is an optimal temperature range that promotes better sleep and overall health.
Scientists consider the optimal temperature for sleep to be between 15°C and 23°C, with the lower end of the range being better for older people and young children. Extremely low temperatures, below 10°C, can have negative effects on the circadian rhythm, leading to sleep disturbances.
One study published in the Journal of Physiological Anthropology explores the effects of temperature on sleep and circadian rhythm. The research suggests that a relatively cooler environment can initiate a drop in body temperature and facilitate the onset of deeper, more restful sleep that is maintained throughout the night.
Alternatively, a warmer environment and higher humidity levels can interfere with the body’s internal temperature by inhibiting heat loss from the body and disrupting the sleep cycle.
Sunlight
Sunlight exposure is a key factor in the regulation and synchronisation of the circadian rhythm, the internal 24-hour biological clock that regulates our sleep-wake cycle. Sunlight exposure in the morning promotes alertness and wakefulness during the day and helps achieve restful sleep at night. Alternatively, lack of sunlight exposure during the winter months or exposure to artificial blue light at night can disrupt the circadian rhythm, leading to sleep disturbances.
Several scientists have investigated the relationship between sunlight exposure and sleep patterns, with most of them of the opinion that exposure to natural light, especially in the morning, positively impacts sleep patterns and promotes health.
A study published in 2020 investigated the association between a lack of sufficient sunlight exposure and the incidence of dementia in older adults. The researchers analysed data from more than 1800 participants aged 65 and older who were followed up for an average of 5.6 years.
The study found that participants who reported low sunlight exposure had a significantly higher risk of developing dementia compared to those with higher sunlight exposure. The risk was even higher in individuals with a genetic risk factor for Alzheimer’s disease. The researchers suggest that the association between sunlight exposure and dementia risk may be related to the role of sunlight in regulating circadian rhythm and melatonin production, which are important for brain health.
REM sleep
Rapid eye movement sleep is one of the stages of sleep that occurs periodically throughout the night, usually starting around 90 minutes after we fall asleep. During REM sleep, the eyes move rapidly back and forth behind closed eyelids, and the activity of the brain increases. REM sleep is often associated with vivid dreams and is an important activity for emotion regulation and memory consolidation. The duration of REM sleep typically increases as the night progresses, with the final REM sleep period lasting up to an hour.
Research suggests that people may experience more REM sleep in the winter. One 2005 study included 20 young and healthy adults whose sleep patterns were measured using polysomnography. It was found that participants had a higher percentage of REM sleep in the winter compared to the summer.
However, another study conducted on 36 healthy adults in 2004 found no significant seasonal difference in REM sleep duration. Polysomnography, a multi-parameter sleep study, was used to measure sleep patterns.
While the evidence is conflicting, changes in the duration and timing of daylight hours during the winter may influence REM sleep. More research is needed to fully understand the complex relationship between temperature, seasonal changes, and sleep patterns, and to develop optimal strategies for promoting healthy sleep environments.
What we do know is that getting enough sleep is essential for overall health and wellbeing. Chronic sleep deprivation has traditionally been known to cause a variety of health problems such as diabetes, obesity and cardiovascular disease.
Therefore, it’s important to prioritise sleep and establish good sleep hygiene habits, such as sticking to a consistent sleep schedule, reducing noise in the environment, avoiding blue light exposure before sleeping, wearing something comfortable and creating a relaxing sleep environment.
Do you find yourself needing more sleep in winter? Do your sleeping habits change throughout the year? Let us know in the comments section below.
Also read: Which sleep type are you?
