New publications
The brain senses the changing seasons
Last reviewed: 02.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Recent research by scientists has shown that the brain is able to determine not only the time of day, but also the time of year. As it turns out, special substances allow the body to adjust to the new season.
Changes in daylight hours lead to a number of fluctuations in the body – changes in blood pressure, temperature, hormonal levels, and functions of internal organs. Specialists call such fluctuations internal (biological) clocks or circadian rhythms.
Special substances take part in the restructuring of the body for the new season - chlorides and gamma-aminobutyric acids, the level of which changes with an increase (decrease) in daylight hours.
The human internal clock works independently of external conditions, but partly it depends on certain circumstances, in particular the length of daylight hours.
Various experiments by scientists in this area have shown that artificially extended daytime is harmful to the body, just like working at night. Such disorders cause problems with sleep, changes in hormonal levels, psychological state, and, in addition, problems with conception are possible, especially in women.
Also, the length of daylight hours affects and helps distribute the body's energy resources; when daylight hours change, the functions of brown fat are disrupted, which leads to excessive accumulation of glucose and fatty acids and increases the risk of developing diabetes and heart and vascular diseases.
There was an article in one of the scientific journals in which a team of scientists described how the work of genes and the immune system changes with the change of seasons.
In their work, the specialists analyzed more than 20 thousand genes, of which more than 5 thousand demonstrated "seasonal dependence" (2311 were more active in the summer months, and 2825 in the winter). It is for this reason that many diseases, such as diabetes, cardiovascular diseases, mental disorders, worsen at a certain time of year. For a long time, specialists could not understand what exactly triggers the body's restructuring processes.
A joint study by Japanese and American scientists has shown how exactly the brain regulates the body's internal clock.
The suprachiasmatic nucleus is responsible for the circadian rhythms, it contains neurons that regulate the biological clock. An interesting discovery was that the nucleus has two areas whose cyclic activity depends on the length of daylight hours and does not coincide with the general "schedule".
During their research, specialists noted that the longer the daylight hours, the more the activity of neurons differs in comparison with other cells in the brain.
As already mentioned, the level of chlorides and gamma-aminobutyric acid determines the functioning of the body's internal processes. Researchers have found that the level of these substances changes with an increase (or decrease) in daylight hours, while areas in the suprachiasmatic nucleus that stand out from the general "schedule" help the body determine the season of the year.
This work by specialists proves that the human brain is a more complex mechanism than previously thought, since it is not only capable of counting a 24-hour cycle, but also determining the current season of the year.