Ah, summertime—the season of sunshine, outdoor activities, and relaxation in nature. With longer days and more daylight, it’s no wonder we feel a boost in our mood and energy levels during this time. However, the abundance of light can also have a downside: it may disrupt our sleep patterns. In this blog post, we’ll explore how light affects our circadian rhythm, the research behind summer sleep disturbances, and provide practical tips to help you get better quality shut-eye during the summer months.
The Role of Light in Sleep Regulation
Our sleep-wake cycle, known as the circadian rhythm, is influenced by light. Light exposure affects the production of hormones that are crucial to our sleep patterns. The amount and timing of light exposure can influence the production of these hormones, potentially leading to sleep issues.
Melatonin and Cortisol
One key hormone affected by light is melatonin. Melatonin is often referred to as the “sleep hormone” because it promotes drowsiness and facilitates sleep onset. The production of melatonin is regulated by the suprachiasmatic nucleus (SCN), a small region in the brain that acts as the body’s internal clock. The SCN receives signals from light-sensitive cells in the retina, which communicate information about the presence or absence of light to the brain.1
In the absence of light, such as in the evening or during nighttime hours, the SCN signals the pineal gland to release melatonin.2 The increase in melatonin levels helps to initiate the sleep process and maintain sleep throughout the night.3 However, exposure to light, especially bright or blue-enriched light, can suppress melatonin production, making it more difficult to fall asleep.
On the other hand, light exposure also influences the production of cortisol, often called the “stress hormone.” Cortisol follows a diurnal pattern, with higher levels in the morning to help us wake up and lower levels in the evening to prepare us for sleep.4 Exposure to natural light in the morning helps regulate cortisol levels, signaling the body to wake up and be alert. On the other hand, reduced light exposure in the evening allows cortisol levels to decrease, promoting relaxation and sleep.4
Different Types of Light Exposure
In modern society, where artificial lighting is prevalent, it is essential to be mindful of our exposure to light, especially in the evening. Implementing strategies to minimize exposure to bright lights, such as dimming indoor lighting and using warm or amber-colored light bulbs, can help promote the production of melatonin and support the natural sleep-wake cycle.
Additionally, technological advancements have led to the widespread use of electronic devices with screens that emit blue light. Blue light has been found to have a particularly potent effect on melatonin suppression.5 Therefore, limiting screen time and using features such as night mode or blue light filters on electronic devices can help mitigate the impact of blue light on sleep.
The Effect of Longer Days
One key factor contributing to summer sleep disturbances is extended daylight. The additional light present in the evening may shift our circadian rhythms, causing us to go to bed and wake up later.6 During the summer, when daylight lasts longer into the evening, our exposure to light is prolonged. This can lead to various factors that contribute to sleep disturbances.7
One such factor is increased social activities and staying out later in the evening. During the summer, people often take advantage of the pleasant weather and engage in outdoor gatherings, parties, or other recreational activities that keep them awake and active for longer. Social stimulation and exposure to bright light during these activities can further delay sleep onset.
Research on Summer Sleep Patterns
A 2019 study shed light on the impact of summer on sleep duration. The study involved 1,388 participants of different age groups who reported their sleep habits during each season.8 The findings revealed that, on average, people slept about 12 minutes less in the summer compared to winter.
Interestingly, the study revealed a discrepancy in sleep duration changes among different age groups. Older participants experienced a more significant decrease in sleep duration during the summer, while adolescents showed no change. This difference in sleep patterns can be attributed to the natural shift in our body clocks as we age.
As we grow older, there is a gradual change in our circadian rhythm, which is our internal body clock that regulates our sleep-wake cycle. This change often results in an earlier wake-up time in the morning for older individuals, regardless of the bedtime.9 Consequently, when the summer days are longer, and there is more daylight in the morning, it can lead to a shorter overall sleep duration for older individuals.
On the other hand, adolescents tend to have more flexible sleep schedules, particularly during summer break. They often have fewer responsibilities and can adjust their sleep patterns to compensate for the extended daylight. This adaptability allows them to maintain a relatively stable sleep duration throughout the year, regardless of the seasonal variations in light exposure.10
It’s important to note that this study was conducted in Japan, and sleep patterns can vary across different regions and cultures. However, the findings provide valuable insights into the potential impact of summer on sleep duration and highlight the importance of considering age-related differences in sleep patterns.
Five Tips for Better Sleep in Summer
1. Mindful Light Exposure: Since our brains cannot distinguish between artificial and natural light, it’s crucial to limit exposure to artificial light, especially blue light from devices, within 30 to 60 minutes before bedtime.11 This practice helps preserve melatonin production and supports a healthy circadian rhythm.
2. Utilize Daylight for Activity: Take advantage of the extra daylight hours by engaging in outdoor activities. Regular aerobic exercise during the day can promote better sleep quality at night.12
3. Create a Cool Sleep Environment: Cooler temperatures facilitate better sleep. Set your thermostat between 65°F and 70°F and keep your bedroom cool by drawing shades during the day.13 Taking a warm shower before bed can also help initiate the temperature drop that aids in falling asleep.14
4. Maintain Sleep Consistency: Stick to a regular sleep schedule, even during the summer months. Consistency supports your body’s natural sleep-wake patterns and helps regulate your circadian rhythm.
5. Consider Time Off: If possible, take time off work during the summer to prioritize sleep and reset your natural sleep schedule. By doing so, you can start the fall season feeling well-rested.
Learn More
Summer’s benefits, like more sunlight and outdoor activities, can disrupt sleep. Somnology provides comprehensive sleep solutions through SLaaS®, SomnoRing®, and our mobile app, streamlining the diagnosis experience. Learn more in our blog.
References:
- Doghramji K. (2007). Melatonin and its receptors: a new class of sleep-promoting agents. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 3(5 Suppl), S17–S23.
- Masters A, Pandi-Perumal SR, Seixas A, Girardin JL, McFarlane SI. Melatonin, the Hormone of Darkness: From Sleep Promotion to Ebola Treatment. Brain Disord Ther. 2014;4(1):1000151.
- Costello RB, Lentino CV, Boyd CC, O’Connell ML, Crawford CC, Sprengel ML, Deuster PA. The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature. Nutr J. 2014 Nov 7;13:106.
- Hirotsu, C., Tufik, S., & Andersen, M. L. (2015). Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep science (Sao Paulo, Brazil), 8(3), 143–152.
- Green A, Cohen-Zion M, Haim A, Dagan Y. Evening light exposure to computer screens disrupts human sleep, biological rhythms, and attention abilities. Chronobiol Int. 2017;34(7):855-865.
- Fisk AS, Tam SKE, Brown LA, Vyazovskiy VV, Bannerman DM, Peirson SN. Light and Cognition: Roles for Circadian Rhythms, Sleep, and Arousal. Front Neurol. 2018 Feb 9;9:56.
- Melrose S. (2015). Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression research and treatment, 2015, 178564.
- Suzuki, M., Taniguchi, T., Furihata, R., Yoshita, K., Arai, Y., Yoshiike, N., & Uchiyama, M. (2019). Seasonal changes in sleep duration and sleep problems: A prospective study in Japanese community residents. PloS one, 14(4), e0215345.
- Duffy JF, Zitting KM, Chinoy ED. Aging and Circadian Rhythms. Sleep Med Clin. 2015 Dec;10(4):423-34.
- Anderson JAE, Campbell KL, Amer T, Grady CL, Hasher L. Timing is everything: Age differences in the cognitive control network are modulated by time of day. Psychol Aging. 2014 Sep;29(3):648-657.
- Gooley, J. J., Chamberlain, K., Smith, K. A., Khalsa, S. B., Rajaratnam, S. M., Van Reen, E., Zeitzer, J. M., Czeisler, C. A., & Lockley, S. W. (2011). Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. The Journal of clinical endocrinology and metabolism, 96(3), E463–E472.