Why You Feel Sleepier in Autumn

How do you know when it’s autumn? Is it your first sighting of a pumpkin latte, or is it when your commute suddenly descends into darkness? There’s a difference of opinion on when autumn officially starts: the meteorological autumn begins on the 1st September; however, it can also be defined by the equinox on the 22nd or 23rd September. The equinox is one of the two times in a year when the sun crosses the plane of the Earth's equator, and day and night are of equal length.

Apart from bringing in a trail of leaves every time you’re back from a walk, you might start to notice that you feel much more tired in autumn. So why do we feel sleepier during these months of the year? Less light exposure, the temperature and your hormones all contribute to feeling more tired.

How does less daylight affect circadian rhythm?

Several scientific studies show that reduced daylight disrupts our internal clock (aka our circadian rhythm). Our bodies have different hormonal responses which control our sleep-wake cycle.

SCN

Your master clock lives in the suprachiasmatic nucleus (SCN). It syncs to the 24-hour day using daylight as a time cue, detected by cells in your eyes. Short and dark autumn days deliver less light intensity and fewer light minutes, so the SCN receives a faint signal, and its rhythm can delay, drift or become less robust.

Melatonin

Melatonin is a hormone produced by the pineal gland in the brain that regulates the sleep-wake cycle. In simple terms, darkness signals to your body to produce more melatonin – communicating to your body it’s time to sleep. In autumn, the days are shorter, so you feel sleepy earlier.

Cortisol

A steroid hormone produced by the adrenal gland, cortisol plays a role in the stress response. Helping with your sleep-wake cycle, cortisol peaks just after waking and then tapers at night. Less daylight plus bright evenings disrupts this curve—less morning get-up-and-go, more midday slump, and a ‘wired but tired’ evening.

Serotonin

A neurotransmitter and hormone produced by the gut and your brain, serotonin regulates bodily functions, mood, digestion and sleep. This is reduced when there’s less sunlight. Serotonin also helps you to produce melatonin.

What is the Hibernation instinct?

The ‘hibernation instinct’ is an animal's built-in drive to hide away when conditions are harsh (usually winter). Still, as human beings, we can also feel inclined to a low-energy state as it starts to get colder. Guided by our internal clocks and hormones that respond to cues like shortening day length, falling temperatures, and less daylight, we feel a draw to stay cosy and warm indoors.

Does heat make me feel sleepy?

You may relish the thought of hunkering down on the sofa in a heated blanket after a long day at work, but heat makes you feel drowsy. You actually need to feel cooler to promote sleep – approximately a temperature of 18–20°C. If you’re too warm, you’ll feel restless and sweat; it’ll also reduce the amount of deep sleep you get.

Bamboo is naturally thermoregulating and highly breathable, so if you’re too hot in bed, it’ll keep you dry and comfortable, and correct your temperature for a deep restorative sleep. Treat yourself to a duvet day when the weather gets dark and cold – wrap yourself up in the Panda Cloud Bamboo Duvet. Fluffy and snug, it’s made from super-soft bamboo for cloud-like comfort all year round. With a 10.5 tog rating and a 300 thread count, you’ll find it hard to emerge from under it.

Is my mood affected by lower serotonin levels?

As serotonin helps to regulate mood, sleep, appetite, and impulse control in the brain, when serotonin activity is reduced, people can experience lower mood, irritability, anxiety, poorer sleep, less energy and more impulsivity. An extreme form of altered mood in the autumn and winter is known as SAD.

SAD

Seasonal Affective Disorder, or winter depression, is a form of depression that follows a seasonal pattern, most often starting in the autumn and easing in spring when daylight increases. Recognised as recently as the 1980s, according to the NHS, SAD affects approximately 2 million people in the UK and 12 million across northern Europe. People who live closer to the poles are more affected by reduced sunlight exposure in these regions.

If your tiredness comes with persistent low mood, oversleeping, cravings, or loss of interest, it could be SAD. It’s treatable — talk to your GP about light therapy, CBT, or antidepressants if needed.

Physical Tiredness vs Emotional Fatigue

If you want to know the exact source of your tiredness, and whether it is your hormones or you’re tired from work, home responsibilities or other health issues, check below the differences we’ve outlined between physical tiredness and emotional fatigue.

Physical Tiredness

Heavy limbs
Sleepiness
Lack physical motivation rather than mental
Slow reactions
You feel better after rest
Muscle soreness

Emotional Fatigue

Overwhelmed
Easily irritated
Insomnia due to racing thoughts
Poor focusHeadaches
Lack of mental motivation to do things
Knot in the stomach

Do changes in lifestyle factors contribute to tiredness?

The Danes have a word for the happiness evoked by cosy feelings from staying indoors: hygge. While eating rich and indulgent food and a day of doing nothing is good for you now and again, if you make a habit of it, this contributes to tiredness. Less time spent outdoors, comfort eating, and fewer workouts all lead to feeling sluggish, a slower metabolism, and disrupted sleep.

Our Bamboo Mattress Topper will refresh both your mattress and your sleep routine. Designed with gel-infused memory foam, HydroFoam™, you’ll receive adaptive support, aligning the spine as you sleep. Thermoregulating, antibacterial and hypoallergenic, you’ll feel rejuvenated after just one night.

How can I feel more energetic in autumn?

Despite the lack of sunlight and the lower temperatures that make you feel sleepier, there are tried-and-tested ways to boost your energy levels.

Here are some tips to add a spring to your step in the autumn.

Maximise your daylight exposure: take morning walks to increase your vitamin D levels.
Keep a consistent sleep schedule – go to bed and wake up at the same time.
Stay active even on grey days.
Adjust your diet with lighter, energising meals with slow-burning food groups such as grains, eggs, avocado, chicken, oats and brown rice
Use warm light rather than bright light in the evenings to support healthy sleep rhythms. Limit blue light exposure from screens.

Conclusion

With shorter days and the sun appearing less often, feeling sleepier in the colder months is normal. It’s a natural shift in rhythm. As light levels drop, your brain produces more melatonin, your sleep hormone, and less serotonin, the mood-boosting chemical that keeps you alert. Combine that with more cosy nights in and comfort-food cravings, and it’s no surprise you’re stifling yawns regularly.

Work with the season: get outside for daylight exposure, keep a consistent sleep schedule, eat balanced meals, and move your body regularly. With a few mindful changes, you can stay energised — and even enjoy the slower, restorative pace that autumn naturally invites. Don’t fall into the eat, sleep, repeat pattern – make sure you try to find ways to spark joy in the darkness.