Longer days and lighter evenings often arrive with a sense of energy and openness. But for many people, this season also brings unexpected difficulties such as increased restlessness, disrupted sleep, irritability, and a general sense of being off balance.
While summer is often associated with vitality and joy, it can have a significant impact on your internal rhythms, particularly your sleep. Seasonal sleep problems are not only frustrating but can also have a negative affect on your mental health. Studies indicate that on average, people get 30 minutes less sleep per night in the summer compared to other seasons.
If you’ve found yourself tossing and turning under the duvet, waking up groggy despite the sunshine, or feeling more emotionally reactive than usual, you’re not alone. These shifts often have less to do with your habits and more to do with how the brain and body respond to changes in light, temperature, and routine.
In this blog, I’ll explore the neuroscience behind seasonal sleep problems, how they affect your mood, and what you can do about it.
I’m Dr Sonney Gullu-McPhee, a clinical psychologist and an ISST-certified advanced schema therapist. I’ll help you overcome the mood changes that you experience due to seasonal sleep problems and help you lead a more emotionally balanced summer.
Get in touch with me to book a session today.
The Science Behind Seasonal Sleep Disruption
Your body and brain are governed by an internal biological clock known as the circadian rhythm. This rhythm regulates not only your sleep-wake cycle but also hormone release, body temperature, digestion, and even mood. One of the key elements that governs this internal rhythm is light.
Extended daylight hours during the warmer months delay the natural production of melatonin, the hormone responsible for preparing the body for sleep (Czeisler et al., 1999). The delay in release or suppression of melatonin can lead to sleep disruption, making it harder to wind down and fall asleep naturally. Elevated temperatures can also interfere with sleep, as the brain requires a drop in core body temperature to initiate and maintain restful sleep (Murphy & Campbell, 1997).
In addition to environmental factors, seasonal changes often bring disruptions to routine. Social events, travel, and irregular schedules interfere with consistent sleep patterns. This irregularity can throw off your body clock, causing sleep disruption, making it more likely that you’ll wake up feeling unrefreshed.
Insomnia and Its Impact on Mental Health
Insomnia involves persistent difficulty falling asleep, staying asleep, or waking too early and being unable to get back to sleep. What makes insomnia particularly difficult is that it often becomes a cycle. Worrying about not sleeping raises arousal levels and makes it even harder to rest the following night. Over time, the anticipation of poor sleep itself becomes a trigger for sleeplessness.
Research has consistently shown that disturbed sleep patterns, especially when chronic, impacts almost every area of emotional functioning. Even short-term sleep loss can significantly impair mood regulation, reduce stress tolerance, and increase the risk of anxiety and depression (Baglioni et al., 2011; Walker, 2017).
Dr Matthew Walker, neuroscientist and author of Why We Sleep, describes sleep as the single most effective thing we can do to reset our brain and body health each day. According to his research, just one night of four to five hours of sleep can lead to a 70 percent reduction in natural killer cell activity, an essential part of the immune system, and increases emotional reactivity due to hyperactivity in the amygdala (Yoo et al., 2007).
Sleep also plays a vital role in memory consolidation, emotional processing, and executive functioning. Without adequate sleep, the brain’s prefrontal cortex, which is responsible for rational thought and emotional regulation, becomes less active. At the same time, the amygdala, the brain’s alarm system, becomes more sensitive. This imbalance can explain why everything feels more intense, overwhelming, or hopeless when you’re sleep-deprived.
Why Sleep is Foundational for Mental Wellbeing
Sleep is not passive rest. It is an active, restorative process during which the brain clears out toxins, consolidates emotional experiences, and repairs the stress systems that regulate mood and resilience (Xie et al., 2013).
Insufficient sleep is both a symptom and a cause of mental health difficulties. Numerous longitudinal studies have found that poor sleep increases the likelihood of developing depression, anxiety, and emotional dysregulation. In fact, chronic insomnia is one of the strongest predictors of new-onset major depressive disorder (Ford & Kamerow, 1989).
People who experience sleep cycle disruption often report low mood, heightened irritability, negative self-talk, and an inability to cope with everyday stress. From a psychological perspective, poor sleep erodes the internal resources we rely on for emotional regulation, identity stability, and interpersonal functioning.
What You Can Do to Support Sleep During Heatwave
Improving sleep is about sending consistent, supportive signals to your brain that it is safe to rest. Here are some neuroscience-based strategies that can support better sleep, especially when you are experiencing seasonal sleep problems.
Get early morning light
Exposure to natural light within 30 minutes of waking helps reset the body’s internal clock, increases cortisol, and supports evening melatonin production. Even on cloudy days, natural light is significantly more powerful than indoor lighting in regulating circadian rhythms (Khalsa et al., 2003).
Support the body’s natural temperature drop
If you’re able to, lower the temperature in your bedroom to between 16 and 19 degrees Celsius. Taking a warm shower or bath about 90 minutes before bed can help the body cool down more efficiently, as it causes heat to be drawn to the skin’s surface, allowing your core temperature to drop (Murphy & Campbell, 1997).
Slow the breath to shift the brain
Practising slow, controlled breathing, such as the 4-7-8 technique, can help engage the parasympathetic nervous system, reduce heart rate, and prepare the brain for sleep. Research shows that slow breathing increases vagal tone and reduces cortisol levels (Zaccaro et al., 2018).
Keep your wake-up time consistent
Even if your bedtime varies, waking at the same time each morning stabilises your circadian rhythm and improves sleep quality over time (Wright et al., 2012).
Process mental noise with self-compassion
If your mind becomes active at night, try journaling or writing a compassionate letter to yourself. This can help calm internal criticism, settle emotional intensity, and reduce the mental load that keeps sleep at bay.
When Sleep Problems Reflect Something Deeper
Sometimes, disturbed sleep patterns are not just behavioural, they are emotional. If your nervous system feels constantly on alert, if you find it hard to feel relaxed even when you’re tired, or if your thoughts become louder at night, it might be time to explore why.
In my work as a clinical psychologist, I support people in understanding the underlying emotional and psychological factors that keep their bodies in a state of fight or flight. Using a blend of Schema Therapy, Cognitive Behavioural Therapy and Compassion-Focused Therapy, we can work together to gently challenge the internal patterns that interfere with rest.
This may include exploring early experiences of emotional deprivation or perfectionism that now keep your mind busy and your body tense. Therapy can offer a safe, consistent space to reconnect with your sense of safety and begin to shift how you relate to rest, vulnerability, and emotional needs.
Final Thoughts and How to Get Support
Sleep is a biological foundation that supports your emotional, cognitive, and physical well-being. During seasonal changes, when environmental and social rhythms shift, it becomes even more important to pay attention to the signals your body is sending.
If you are finding that seasonal sleep problems are affecting your mood, your relationships, or your sense of self, therapy can help. You don’t need to manage this alone. Together, we can explore what your mind and body need to feel safe enough to rest with my sleep deprivation therapy.
I offer therapy in Petersfield, Hampshire and online across the UK. If you would like to take the first step toward more restorative sleep and emotional clarity, you can get in touch by calling +44 7584 354041, emailing me at info@drmcphee.co.uk, or by filling out the secure contact form here.