Why do we sleep worse in summer? Not all insomnia has the same origin.

Every summer, the number of people reporting difficulty sleeping increases. However, attributing it solely to the heat is an oversimplification.

Nighttime rest depends on a complex interaction between body temperature, circadian rhythm, melatonin secretion, autonomic nervous system activity, and neuroendocrine status. During the summer months, several of these physiological mechanisms can be simultaneously altered.

1. Body temperature no longer facilitates sleep onset

To initiate sleep, the body needs to decrease its core body temperature by approximately 0.5 to 1 °C.

This decrease activates physiological mechanisms related to peripheral vasodilation and is one of the signals the hypothalamus receives to promote sleep onset.

When ambient temperature remains high during the night, this mechanism becomes less efficient.

As a consequence:

• sleep latency increases;
• deep sleep (N3) decreases;
• more nighttime awakenings occur;
• the feeling of restfulness upon waking decreases.

 

It is no coincidence that numerous studies have shown that heatwaves reduce both the duration and quality of sleep.

2. Prolonged light exposure alters circadian rhythm

Summer also modifies the main biological signal that regulates our internal clock: light.

The retina transmits this information to the suprachiasmatic nucleus of the hypothalamus, which is responsible for synchronizing circadian rhythms.

When light exposure is prolonged for more hours:

• the physiological release of melatonin is delayed;
• the feeling of sleepiness at the usual time decreases;
• the natural time for rest shifts.

 

In particularly sensitive individuals, this small delay is enough to disrupt sleep onset.

Melatonin is precisely the main hormone synchronizing the sleep-wake rhythm, and its production directly depends on environmental darkness.

3. Summer also increases physiological stress

Paradoxically, although we tend to associate summer with rest, for many people it means an increase in biological stress:

• poorer nighttime recovery;
• schedule changes;
• frequent travel;
• increased social activity;
• digestive disturbances;
• dehydration;
• increased cortisol in people with high work demands.

 

When the nervous system remains in a state of hyperactivation, the problem is no longer just melatonin.

In these cases, symptoms such as:

• difficulty unwinding;
• repetitive thoughts before sleep;
• shallow sleep;
• frequent awakenings;
• feeling unrested.

 

Scientific evidence shows that chronic stress promotes the depletion of magnesium stores, while magnesium deficiency increases susceptibility to stress, establishing a vicious cycle between both situations. Furthermore, magnesium participates in the regulation of inhibitory neurotransmitters such as GABA and modulates the stress response mediated by catecholamines and glucocorticoids.

Not all insomnia should be approached in the same way

From a physiological point of view, we can differentiate two very frequent profiles.

When the problem is an alteration of the circadian rhythm

Patients who:

• take a long time to fall asleep;
• have disordered schedules;
• experience jet lag;
• work shifts;
• maintain good sleep quality once asleep.

 

In these cases, the main goal is to resynchronize the biological clock.

Administering Melatonin before bedtime helps reduce sleep latency and promotes higher quality rest. Our formulation also includes Pyridoxal-5'-Phosphate (P-5'-P), the metabolically active form of vitamin B6, which participates in the synthesis of serotonin and melatonin and enhances their physiological utilization.

When the problem is nervous system hyperactivation

There is another group of patients who are sleepy, but unable to "switch off."

They predominantly experience:

• sustained stress;
• anxiety;
• muscle tension;
• night awakenings;
• unrestorative sleep.

 

In these situations, it is more logical to act on the regulation of the nervous system than to solely provide melatonin.

Magsense® combines:

• Highly bioavailable Albion® magnesium bisglycinate;
• Ashwagandha Sensoril®, a standardized extract with clinical evidence in stress reduction;
• Pyridoxal-5'-Phosphate, involved in neurotransmitter synthesis and magnesium metabolism.

 

This combination is designed to promote neuromuscular relaxation, modulate the stress response, and contribute to higher quality rest when the problem's origin is physiological hyperactivation.

The key is to identify the cause

Poor sleep in summer doesn't always mean a melatonin deficiency.

In some patients, the main problem is a delayed circadian rhythm; in others, it's nervous system hyperactivation, or a combination of both mechanisms.

Understanding the physiology behind insomnia allows for individualized approaches and selection of the most appropriate strategy for each person, rather than applying a universal solution to problems with different biological mechanisms.

Because in medicine, and also in clinical nutrition, the best treatment always begins by understanding the cause.

References

1. Minor K, Bjerre-Nielsen A, Jonasdottir SS, Lehmann S, Obradovich N. Rising temperatures erode human sleep globally. One Earth. 2022;5(5):534-49. doi:10.1016/j.oneear.2022.04.008.
2. Xu X, Wang Z, Luo M, Zhang H. The effects of personal comfort systems on sleep: A systematic review. Renew Sustain Energy Rev. 2025;205:115474. doi:10.1016/j.rser.2025.115474.
3. Riemann D, Nissen C, Palagini L, Otte A, Perlis ML, Spiegelhalder K. The neurobiology, investigation and treatment of chronic insomnia. Lancet Neurol. 2023;22(2):174-86. doi:10.1016/S1474-4422(22)00450-1.
4. Arendt J. Melatonin and the mammalian circadian system. Sleep Med Clin. 2022;17(2):145-57.
5. Pandi-Perumal SR, Cardinali DP, Brown GM. Melatonin and the circadian system: Basic physiology and clinical implications. J Pineal Res. 2023;75(3):e12873.
6. Pickering G, Mazur A, Trousselard M, Bienkowski P, Yaltsewa N, Amessou M, et al. Magnesium status and stress: The vicious circle concept revisited. Nutrients. 2020;12(12):3672. doi:10.3390/nu12123672.
7. Gröber U, Schmidt J, Kisters K. Magnesium in prevention and therapy. Nutrients. 2023;15(5):1186.
8. Mah J, Pitre T, Cooke M, et al. Oral magnesium supplementation for insomnia in adults: A systematic review and meta-analysis. BMC Complement Med Ther. 2021;21:125.
9. Cheah KL, Norhayati MN, Husniati Yaacob L. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One. 2021;16(9):e0257843. doi:10.1371/journal.pone.0257843.
10. Lopresti AL, Smith SJ, Drummond PD. Ashwagandha (Withania somnifera) for the treatment of stress and anxiety: A systematic review. J Clin Med. 2023;12(9):3021.
11. Buguet A. Sleep under extreme thermal conditions: Effects of heat on sleep physiology. J Therm Biol. 2023;116:103643.
12. Irwin MR. Sleep and inflammation: Partners in sickness and in health. Nat Rev Immunol. 2023;23(6):340-52. doi:10.1038/s41577-022-00850-w.