As we are immersed in the joys of summer, there is an aspect of this season that often goes overlooked – its impact on our sleep patterns. Let’s dive into the fascinating realm of circadian rhythm and explore practical, holistic solutions to ensure a good night’s sleep, even during the longest days of the year.

Summertime Sleep Disruption

From Thomas Easley, RH

Our sleep-wake cycle is an intricately coordinated physiological process governed by an internal body clock known as the circadian rhythm. The ‘conductor’ of this internal symphony is a small brain region known as the suprachiasmatic nucleus (SCN). Located in the hypothalamus, this bilateral structure consisting of about 20,000 neurons plays a crucial role in synchronizing our body’s functions with the day-night cycle.

The SCN receives light information directly from the retina via the retinohypothalamic tract, allowing it to synchronize our internal processes with the external light-dark cycle. On a molecular level, the SCN contains a self-sustaining clock mechanism formed by a set of core clock genes operating through transcriptional-translational feedback loops. The precision of this feedback mechanism ensures a cycle length of approximately 24 hours, giving our circadian rhythm its name, derived from “circa diem” (approximately a day).

Image via Wikipedia.

A Note on Nerding Out

I’m a physiology nerd. I love learning the intricate mechanisms by which our body functions. The level of detail that intrigues me is beyond what you need to know to understand the general function of a tissue, but researching and then writing about super detailed physiology helps me understand and remember it better. So, with that in mind I will occasionally be indulging my inner geek in sections clearly labeled “Nerd Out.” Please feel free to gloss over these sections to get to the juicy helpful bits.

SCN Nerd Out

The SCN is divided into two main compartments: the ventrolateral (or “core”) and dorsomedial (or “shell”) divisions. These compartments have different neuronal populations and connections, and they play different roles in the SCN’s function. The ventrolateral SCN receives light information directly from the retina via the retinohypothalamic tract and contains neurons that produce vasoactive intestinal polypeptide (VIP). The dorsomedial SCN contains neurons that produce arginine vasopressin (AVP) and receives inputs from the ventrolateral SCN.

Light information, primarily blue light, is detected by intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina, which contain the photopigment melanopsin. These cells project directly to the SCN via the retinohypothalamic tract. This light information resets the SCN, keeping it synchronized with the external light-dark cycle.

At the molecular level, the circadian rhythm in SCN neurons is generated by a set of core clock genes through transcriptional-translational feedback loops. The positive limb of this loop is primarily composed of the CLOCK (Circadian Locomotor Output Cycles Kaput) and BMAL1 (Brain and Muscle ARNT-Like 1) proteins, which form heterodimers that bind to E-box elements in the promoter regions of their target genes, including the period (Per1, Per2, and Per3) and cryptochrome (Cry1 and Cry2) genes. The PER and CRY proteins form complexes that, after a delay, inhibit the activity of the CLOCK:BMAL1 complex, thus reducing their own transcription. This feedback loop takes approximately 24 hours to complete, generating the circadian rhythm.

The SCN communicates timing information to the rest of the body through a variety of signaling mechanisms, including neural, humoral, and thermoregulatory signals. For example, it controls the rhythmic release of melatonin from the pineal gland primarily through a multisynaptic pathway that involves the paraventricular nucleus of the hypothalamus, the intermediolateral nucleus of the spinal cord, and the superior cervical ganglion. The SCN also regulates rhythms of glucocorticoid release from the adrenal gland via its control of the hypothalamic-pituitary-adrenal (HPA) axis.

The SCN exhibits a remarkable degree of plasticity. For instance, “splitting” is a phenomenon where the bilateral SCN can maintain two different circadian rhythms. This typically occurs under conditions of constant light, reflecting the independent oscillation of the left and right SCN. The SCN can also be entrained by non-light cues, such as eating schedules and social cues, although light is the most potent entraining agent.

While the SCN is the central pacemaker, peripheral clocks exist in nearly all cells of the body, and these can be entrained by the SCN but also by other factors such as eating times. The coordination between the central and peripheral clocks is critical for optimal health, and disruption of this coordination can contribute to various disorders, including metabolic, cardiovascular, and sleep disorders.

Lastly, while the SCN is critical, it’s not the only structure that influences circadian rhythms. Other brain regions, such as the olfactory bulb and the locus coeruleus, have been shown to exhibit circadian rhythms and could have impacts on specific aspects of physiology and behavior, but this nerd out is already longer than I’d like, so let’s move on.

Summer’s Impact on Sleep: A Delayed Night’s Slumber

During the extended daylight hours of summer, circadian rhythm can face challenges. Increased light exposure, especially later in the day, can postpone melatonin secretion, the hormone signaling to our bodies that it’s time for sleep.

This can lead to delayed sleep phase disorder, where individuals like me struggle to fall asleep at a conventional time and consequently face difficulties waking up early.

The ramifications of this are not uniform across the board, and certain groups are more susceptible to these changes, particularly adolescents, whose internal clocks are naturally inclined toward later bedtimes.

Those with existing sleep disorders or mental health challenges, such as depression or bipolar disorder, might also experience exacerbated symptoms due to the disruptions in sleep timing. The elderly, who often exhibit advanced sleep phase disorder (going to bed and waking up earlier than desired), may find their sleep further fragmented during summer. Finally, individuals with a genetic predisposition towards being ‘night owls’ may struggle to adjust to societal norms, leading to ‘social jetlag.’

Natural Interventions for Circadian Rhythm Balance

Interventions to combat summer sleep disruptions come in a variety of forms. Traditional nervines, including hops, skullcap, lemon balm and passionflower are frequently used for insomnia.

There are terminology subtleties (that few herbalists agree upon) when talking about nervine herbs that are worth exploring. I think* of four main types of nervines to consider when faced with sleep challenges.

(*at this moment in time and I reserve the right to change my mind)

Nervine Tonics

Nervine Tonics tonify the nervous system’s response to challenges, increasing flexibility and capacity for adaptation. These are not remedies you take when you feel stressed and need to calm down (though some work quickly enough). Nervine tonics are remedies you take preventatively if you’re prone to burnout, starting to feel fried, are recovering from burnout, or have any sort of chronic illness or pain. They work best when they are taken consistently, even when you’re feeling fine or having a good day. The deepness of their actions do not start to become apparent until around six weeks of consistent use. It’s often when people run out that they notice they are feeling more taut, irritable, and more easily overstimulated. Some people feel profound effects quickly, but as a general rule these herbs are defined by their subtle, gentle, and deep resiliency building action.

Among my favorite Nervine Tonics are: Milky Oats, Ashwagandha, and Skullcap (fresh tincture).

Milky Oats – is a calming, uplifting, gentle and moistening nervine tonic that combines well with every other nervine, and is appropriate for long term use. It works best for people with mental and/or physical exhaustion/burnout, who are irritable and lack focus and maybe even feel hopeless about recovering from their burnout or chronic illness. It must be a fresh tincture or glycerite, I think dried is ineffective.

Photo via GaiaHerbs.

Skullcap – is indicated for when lights, noises and smells are overwhelming (sensory hypersensitivity); when people are at the “end of their rope”; emotionally labile and reactive; recovering from mental breakdown; or recovering from stimulant overuse.

Ashwagandha (root) – is a balanced grounding and nourishing nervine tonic that helps anxiety, insomnia, exhaustion, and often, hypothyroidism. It improves quality of sleep, and decreases sleep onset latency and might owe many of its effects on the nervous system to its effects on sleep. (Note that the aboveground portion of the plant, not the root, is shown here).

Nervine Sedatives

Nervine Sedatives are often thought of as sleep inducing, but they sedate mental overactivity rather than induce sleepiness. If you’re sleep deprived with a lot of mental chatter, reducing that mental chatter can make you feel the sleepiness that was already present, but in people not sleep deprived this class doesn’t consistently induce drowsiness unless used in very large doses. Passion flower and Blue Vervain are good examples of Nervine Sedatives.

Passionflower is specifically indicated for circular thinking – imagine two squirrels frantically chasing each other in circles until they clash into a ball of fur and squeals only to resume the chase moments later.

Blue Vervain is specifically indicated for stiff necked overachieving list makers (mental rigidity + overactivity). If I’m sleepy, but can’t let go of the day, Blue Vervain slowly drains the thoughts and tension away. If I’m not sleepy and take it, I feel like I’ve mastered the art of Zen, and occasionally wonder what happened to the thoughts in my head. If I have sleep debt to repay the lack of thoughts makes it much easier to get to sleep.


Nervine Relaxants

Nervine Relaxants are similar to nervine sedatives in that they don’t inherently induce sleepiness, rather that promote physical relaxation. If your distress manifests in physical tension more than mental overactivity this class of herbs can feel magical!

Lobelia and Black Cohosh are key Nervine Relaxants to think of when distress or insomnia drive structural tension. Sometimes structural tension can lead to pain or discomfort that delays sleep. If you don’t have mental overactivity, but toss and turn and can’t get comfortable in bed even when you’re sleepy, give Nervine Relaxants a try.


Nervine Hypnotics

Nervine Hypnotics (AKA Soporifics) are sleep-inducing herbs. These herbs have been used traditionally to promote relaxation and decrease the time taken to fall asleep, or sleep latency.

With Nervine Tonics, Sedatives and Relaxants the effects are largely subjective. With Nervine Hypnotics there are ways to objectively measure the effects – do you fall asleep faster, is your total sleep time increased?

Unfortunately, once you get past the overtly strong hypnotics, like opium poppy and cannabis, the research is either lacking, or shows mixed results. Instead of analyzing the mediocre research, here are a few things I think of as hypnotics.

Photo via Britannica.

Kava is an interesting herb for a lot of reasons, including its dose dependent action, and variety differences. When using noble varieties (varieties traditionally used by South Pacific peoples), there is a noticeable Nervine Relaxant (skeletal relaxant) effect, followed by a Nervine Sedative effect, eventually followed by an overt Hypnotic effect. In my body this feels like a warming tension relief that starts in my stomach, and slowly works its way outwards. If I’m in a social environment (the best for experiencing the full range of effects of Kava, IMO), I try to slow my consumption when I feel the relaxing effects reach my mind. If I consume enough Kava that the warming numbness makes it way to my fingers, I need to find a bed.

Hops is a strongly bitter cooling herb, that many find hypnotic. I think of it when people have both heat and stagnation signs, along with occasional insomnia. If you get agitated in the evening when you should be winding down, but you also feel stagnant and stuck, like you know you should go to bed, and maybe you’re even sleepy, but something is holding you back from making the decision to go to bed – give hops a try.

Photo via Mountain Rose Herbs.

Skullcap as a fresh tincture is a Nervine Tonic, but when dried and prepared as a tea or fluid extract, its hypnotic properties are brought out. Preparation and dosage shift the actions of many herbs. I think of dried skullcap as a lead herb in evening tea preparations. It’s often combined with tasty, gentle herbs like linden or chamomile.

In the mid-1800s, Lithium was recognized as a hypnotic and sedative before the discovery of its anti-manic properties. Nowadays, it’s primarily associated with the treatment of bipolar disorder, which is an unfortunate pigeonholing of a valuable mineral. While high doses induce an overtly hypnotic effect, they can also be harmful to the kidneys.

Low-dose lithium, such as that found in over-the-counter lithium orotate products, doesn’t overtly sedate but does enhance slow wave sleep that feels deeply restorative, while decreasing REM sleep.

Excessive REM sleep has been implicated in depression and other disorders, a complex subject that should be explored separately.

In cases where individuals fall asleep but then wake several times throughout the night, low-dose lithium may provide a delayed hypnotic effect. There are several conditions, like sleep apnea, that cause nighttime wakening, and should be ruled out before trying lithium. An added bonus is lithium targets insomnia characterized by unpleasantly vivid dreams or nightmares.

In addition to improving sleep quality and aiding nighttime disruptions, there’s evidence to suggest that lithium possesses neuroprotective and anti-inflammatory properties in the brain. These qualities may contribute to the regulation of circadian rhythm, possibly through lithium’s anti-inflammatory actions on the brain.

This multifaceted influence of low-dose lithium on sleep and brain health adds to its potential as a nuanced intervention for disrupted sleep patterns, extending beyond its widely recognized use in bipolar disorder treatment.

Low-dose lithium, such as that found in over-the-counter lithium orotate products, doesn’t overtly sedate but does enhance slow wave sleep that feels deeply restorative, while decreasing REM sleep.

One more note about herbal hypnotics: It’s important to note that all Hypnotics (herbal or pharmaceutical) are most helpful for transition times and occasional insomnia. For chronic insomnia there is a strong argument to be made that behavioral sleep therapy, and CBT-i should be tried before hypnotics, but that’s a discussion for another day.

Meditating as part of stress reduction, and creating a comfortable sleep environment, can contribute to better sleep hygiene.

Sleep Hygiene and Light Exposure

Sleep hygiene refers to a set of practices and habits that are conducive to sleeping well on a regular basis. These practices are essential for maintaining both the quality and quantity of sleep, which in turn supports overall health and well-being. Sleep hygiene includes the following principles:

  1. Consistency: Going to bed and waking up at the same time every day, even on weekends, helps regulate the body’s internal clock.
  2. Environment: Creating a comfortable sleep environment by controlling light, noise, and temperature, and investing in a comfortable mattress and pillows.
  3. Pre-Sleep Routine: Engaging in calming activities before bed, such as reading, meditation, or taking a warm bath, to signal to the brain that it’s time to wind down.
  4. Avoidance of Stimulants: Avoiding caffeine, nicotine, and other stimulants close to bedtime, as they can interfere with the body’s ability to fall asleep.
  5. Mindful Eating and Drinking: Being cautious with food and drink that might disrupt sleep, such as large meals, alcohol, or spicy foods near bedtime.
  6. Physical Activity: Regular physical exercise can promote better sleep, but engaging in strenuous workouts too close to bedtime might interfere with sleep.
  7. Limiting Naps: While brief naps can be beneficial for some, long or late-day naps can negatively affect nighttime sleep.
  8. Technology Restrictions: Reducing exposure to screens, such as computers, tablets, and smartphones, as the blue light emitted can interfere with melatonin production.
  9. Managing Stress: Practicing techniques to manage stress and anxiety, as these feelings can hinder sleep.
  10. Increased Darkness: In the extended daylight of summer, one additional principle can be integrated into basic sleep hygiene: increased darkness. This strategy recognizes the impact of prolonged exposure to light on sleep quality and seeks to mitigate it. Using blackout curtains helps shield against the persistent summer daylight, creating an environment more conducive to sleep. Additionally, wearing an eye mask can provide a personal sense of darkness, further enhancing the body’s ability to transition into sleep.

Our circadian rhythm is most responsive to light exposure in the early morning. If using blackout curtains or an eye mask, seeking exposure to morning sunlight or using a light box can help keep circadian rhythm matched to your normal wake time.


Understanding our bodies’ intrinsic rhythm is key to combating summer sleep disruptions. Using a multifaceted approach that combines an understanding of our internal biological clock, the judicious use of herbal and supplemental sleep aids, and environmental modifications can help maintain quality sleep during the longest days of the year.