Scientists have explained the reasons for irresistible sleepiness in winter: how to deal with it

People don’t need to hibernate

Many people experience a nagging feeling of lack of sleep in winter. The influence of seasonality on human sleep until February 2023 was considered practically zero. However, a new study has refuted this.

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“If you want to sleep more in winter, you are not alone, – notes Raj Dasgupta, assistant professor of clinical medicine at Huntington Memorial Hospital in Pasadena, California. – Most adults' sleep needs are somewhere between seven and nine hours a night, and that's consistent, no matter how cold or dark it is outside. However, it is in winter that you often feel like you are sleeping more due to the fact that we are losing an hour of daylight.”

Compared to animals, the influence of seasonality on human sleep was considered almost zero until recently. A study published in February 2023 found the opposite: 188 patients who underwent sleep studies at St. Hedwig's Hospital in Berlin slept about an hour longer in winter than in summer.

Wanting or having more sleep in winter may be related to the way light fluctuates throughout the year, or changes in behavior and mental health that may occur.

«Our bodies receive signals from the sun when it's about our circadian rhythm, which means that when it's light outside, we tend to be active. When the sun goes down, you may feel tired,” – Dasgupta emphasized.

Given the earlier production of melatonin in winter, “it would be natural to assume that a healthy person would also require more sleep in winter,” — said Carlear Weiss, assistant professor at the California State University Center for Nursing Research.

Light affects not only the quantity, but also the quality of sleep. “REM sleep is highly dependent on light and darkness, so when we have less light during the winter months, the body will essentially overcompensate by producing more REM sleep,” &ldash; noted New York clinical psychologist Joshua Thal, who specializes in sleep problems.

The need for more sleep in winter may also be associated with so-called “social jet lag,” experts say. This means that staying awake on summer nights may be the reason you have trouble falling asleep in winter or feeling the need to compensate for this lack of sleep with more sleep.

Other behavioral causes include «holiday stress, binge eating, drinking alcohol, and skipping exercise.»

Carleara Weiss says humans still don't need to hibernate, nor can we. allow this because of our social and professional obligations. However, we can make adjustments.

Because of how winter light changes can affect our circadian rhythms, getting a little more sleep can help you be more mindful of a schedule that requires you to be outside while it's dark, according to Joshua Tal.

“To help our bodies make the transition from sleep to wakefulness, it is important to have enough light in the morning during the winter months. Along with this, it is important to maintain the same sleep and wake-up times,” – emphasizes Carlear Weiss.

If your work schedule simply doesn't allow for natural light sources in the winter, you can try light therapy as an alternative. This is the main treatment for seasonal affective disorder, which may be another reason you need more sleep during the winter. Treatment involves exposure to a light source of at least 10,000 lux for at least 30 minutes.

“It is very important to make sure that the environment in which you sleep is conducive to sleep,” – Jennifer Martin, a professor at the David Geffen School of Medicine at UCLA and former president of the American Academy of Sleep Medicine, made an important point.