Jet lag pojawia się, gdy człowiek szybko podróżuje przez różne strefy czasowe, przez co jego naturalny zegar biologiczny nie jest już zsynchronizowany z rzeczywistą porą dnia. Zakłóca to równowagę hormonalną, która jest przyzwyczajona do przestrzegania dobrze zdefiniowanego rytmu dobowego. Im więcej stref czasowych przekracza się podczas podróży, tym gorsze są objawy jet lagu: nasz rytm biologiczny potrzebuje czasu na dostosowanie się. Najczęstsze objawy to bezsenność w nocy i senność w ciągu dnia, ogólny dyskomfort i inne objawy somatyczne, takie jak trudności z koncentracją i problemy z układem krążenia. Skutki zdrowotne mogą być wielorakie: senność w ciągu dnia, trudności z zasypianiem i przespaniem całej nocy, słaba sprawność fizyczna, obniżone zdolności poznawcze, wahania nastroju oraz problemy żołądkowo-jelitowe i psychosomatyczne. Upośledzony może być również czas reakcji. W cięższych przypadkach może dojść do chorób układu krążenia, cukrzycy i nowotworów.

W tym przypadku melatonina może skutecznie regulować rytm snu i czuwania, szczególnie podczas lotów w różnych strefach czasowych. Różne badania wykazały, że melatonina może przyspieszyć proces synchronizacji wewnętrznych rytmów z nową strefą czasową. Melatonina okazała się również przydatna w łagodzeniu innych objawów jet lagu. Melatonina jest również idealna dla pracowników zmianowych, którzy często cierpią na zaburzenia snu, ponieważ osoby te – podobnie jak osoby z zespołem jet lag – podlegają częstym zmianom rytmów okołodobowych. Przyjmowanie melatoniny o określonych porach jest ważne, aby zapewnić jej skuteczność w razie potrzeby. Idealnym czasem na przyjmowanie melatoniny może być na przykład godzina między 21:00 a 22:00 w nowej strefie czasowej w przypadku jet lagu lub godzina przed snem w przypadku pracy zmianowej. Dobrym wsparciem dla tego typu chronoterapii może być terapia światłem, która polega na wystawieniu oczu na bezpośredni kontakt z bardzo intensywnym źródłem światła przez krótki czas. W przypadku jetlagu światło powinno być podawane rano w nowej strefie czasowej, a w przypadku pracowników zmianowych – przed nową fazą przebudzenia.

Zaburzenia snu spowodowane przyjmowaniem leków

Wiele leków i/lub stymulantów może mieć negatywny wpływ na uwalnianie melatoniny. Wykazano, że niektóre leki nasenne, takie jak benzodiazepiny, ale także leki nasercowe, takie jak beta-blokery, hamują produkcję melatoniny. Nadmierne spożycie alkoholu i/lub kofeiny (kawy lub czarnej herbaty) może również mieć negatywny wpływ na uwalnianie melatoniny i powodować zaburzenia snu lub niezdrowy sen. W celu wspierania endogennej produkcji melatoniny poprzez przyjmowanie substancji wstępnych, takich jak tryptofan i/lub 5HTP, ważne jest, aby pamiętać, że w starszym wieku człowiek nie jest już w stanie syntetyzować melatoniny z tych substancji. W rezultacie przyjmowanie tych substancji w godzinach wieczornych prowadzi do zwiększonego poziomu serotoniny zamiast melatoniny: zamiast promować sen, produkty te powodują zaburzenia snu spowodowane samym ich spożyciem.

With endogenous sleep disturbances the amount of the produced melatonin is either reduced, or the melatonin is released at the wrong time, even though one is in a normal day/night rhythm.

Delayed Sleep Onset Syndrome

With the delayed sleep onset syndrome a sleep disturbance is present which is caused through a shifted melatonin rhythm. It normally appears among teenagers and young adults which belong to the chronotype “night owls.“ They make night into day, and stay up until the early morning hours, and then sleep into the afternoon. Those affected report chronic sleeplessness.

The delayed sleep onset syndrome of these owls is most easily treated with the help of light therapy in the morning. It is recommended to conduct the light therapy early in the morning in order to shift the sleep-wake rhythm forward. Similar effects can be achieved through taking melatonin in the first evening hours, whether it be fast-releasing or pulsing melatonin. A combination of both therapies is also possible.

 Sleep-Wake Disruption among the Blind (Non-24 Syndrome)

Non-24 is a serious, severe, and chronic disturbance of the day/night rhythm that is especially common among the blind. People with non-24 syndrome are not able to adjust or synchronize their inner clock to the 24-hour rhythm of a day. These people live in their own rhythm that lasts between 24-and-a-half and 25 hours. This leads to the fact that each day they fall asleep and get up 30 -60 minutes later. All the other rhythms of the body, such as body temperature, hormone release, or the height of activity, also shift accordingly.

The goal of a chronobiologically correct therapy is to synchronize the inner clock of the affected people with the 24-hour rhythm of the day. If necessary, this can be done in the mornings through light therapy, as well as through substances that suppress daytime drowsiness. However, this only works for those who are still able to minimally perceive light and dark. For all other patients the nighttime administration of melatonin or similarly acting substances should encourage sleep and serve as a time-keeper for the inner clock to follow.

Different substances can be used to adapt the endogenous rhythm of the blind to that of a normal day/night rhythm: On the one hand, melatonin can be used as a time-giving hormone in the evening. Through the ingestion of melatonin, whether it be a fast-releasing or a pulsing formula, the body is signaled that it is now night. Recently some melatonin-like substances have also become available, such as Tasimelteon (Hetlioz®), which also needs to be taken in the evening and works over the melatonin receptors in the brain to set the inner clock according to the day/night rhythm.

Sleep Disturbances in Old Age and Special Life Situations

Even though a life-prolonging effect has not yet been proven among humans, it is certain the melatonin does positively impact the quality of life, especially among the elderly. The hormone appears to be effective in the treatment of diverse processes which are associated with aging, such as disturbances in the sleep-wake rhythm, lowering of blood pressure and in the correction of immune system deficiencies. It is also assumed that the hormone is helpful in delaying the molecular destruction, cell loss and deterioration of the organism, which are all factors that contribute to ageing.

Due to an age-related decrease of the nightly melatonin level, elderly people often suffer from sleep disturbances. It is currently assumed that every second person over the age of 65 is affected by sleep disturbances. In this instance, the treatment with melatonin has proven itself to be helpful. Studies demonstrated that the use of melatonin not only ensured improved quality of sleep, but also decreased depression and fears. The positive effect of this hormone can be ascribed to its ability to normalize the circadian rhythm. Such a regenerated rhythm can then effect all other physiological processes positively, and can significantly increase the quality of life and possibly be a factor in increasing life expectancy.

A special group of patients are women going through menopause. This stage of life is accompanied by deep-seated hormonal changes that not only lead to sleep problems, but can also evoke other symptoms. The extent to which melatonin secretion changes through this event is still the subject of different investigations. Nevertheless, studies with women in perimenopause have been able to demonstrate that pituitary gland activity, as well as function of the thyroid, can be improved with the ingestion of melatonin. Additionally, most women treated with melatonin reported a general improvement in mood and a significant alleviation of depression. This thesis is supported through the fact that high melatonin concentration in old age—as demonstrated in all previous studies—improves general wellbeing and can lead to alleviation of age associated illnesses. This effect mirrors the effect of melatonin as a sleep regulator, as well as that of a potent antioxidant. For all humans, including menopausal women, it could be demonstrated that restful sleep significantly improved general wellbeing on the following day.

Sleep Disturbances with Winter Depression

So-called winter depression, also known as seasonal affective disorder (SAD), deals with a special form of depression that is most prevalent in the fall and winter months. The primary symptoms are a suppressed mood, reduction of energy levels and fearfulness, as well as prolonging of sleep time, increased appetite for sweets (ravenous appetite for carbohydrates), and weight gain. On the other hand, depression that is not seasonally characterized is rather accompanied by loss of appetite, weight loss and shortening of sleep. As this type of depression is more frequently found in regions that have long winters with long nights (for example the polar regions), it is assumed that this people suffer from a disruption in melatonin production. Often these people release melatonin more frequently and for longer periods of time.

Interestingly, a positive effect of exogenous melatonin could still be demonstrated. A small, early evening dose of melatonin in a fast-releasing dosage form can already help to improve the synchronization of the inner clock and the biological day rhythm with the light conditions present during the winter, which significantly improves the emotional state. Additionally, light therapy has also proven itself as a treatment option. When applied in the morning it not only reduces morning melatonin levels, but also impacts the entire rhythm positively.