1) Gravitational Waves (not Gravity Waves) are scientifically hypothesized and shown to be mathematically plausible, for example Gravitational waves carry energy away from their sources leading to orbital decay which can be measured. However no proof of their existence has yet been demonstrated.
19 June 2014:
Yay, they exist! um ... or maybe not
11 February 2016 YES DEFINITELY, for sure.
2) one of the most outstanding breeding cues for people, amphibians, & at least a dozen families of marine organisms: is the moon. Police & hospital entries pick up on the full moon. And it can be shown that there actually is an etiological path to our awareness through bacteria, many of which change behavior according to the position of the sun, moon and horizon (aka time of day).
Life on earth has been around for 4 billion years. During that time it evolved ways to recognize cues to optimize life functions, like when to release spores or breed, estivate, migrate, sleep, wake, etc. In doing so, cells and bacteria change their protein arrangement to fit the occasion, for example to become mobile, inert, permeable, toxic & so forth.
The resulting bio-community lives off it's constituents in such a way that one bugs toxin is anothers ambrosia and chemical defense or optimization strategies make World of Warcraft and Pokemon seem feeble in contrast. Each of those strategies affects it's environment somehow or they wouldn't exist, and often as not they have unplanned side effects on other nearby bugs or cells.
Vertebrates (like humans) are about 70% independent and semi-independent bacteria/fungus/viruses, and 30% dedicated host cells. The host cells depend on these symbiotic bacteria and have digestive systems to feed, farm, cull, & harvest them for nutrients. Sometimes bacterial chemical byproducts (for example from Toxoplasma gondii) have effects on the host equivalent to drugs (such as alcohol or strychnine) that induce stress, sleep, craving, hallucination, euphoria, or depression. 
This hypothesis suggestsan association between the two, that people are also affected by the chemical response to gravitational stimulus of their parasite organisms. These organisms are locked into their life cycles    by responding to solar and lunar cycles. Deep sea organisms respond to the moon, such as the sea anemone Allantactis parasitica (Wikipedia) which synchronises its breeding activity with the phases of the moon even when moonlight doesn't penetrate to those depths, gravitational pull does.
There are many people who have no confidence or reason to believe in gravitational (astrological) influences, possibly because those people don't have a microbiome that responds to them. A google search will show biological breeding cycles occurring on practically any time interval from a few hours to a dozen + years (such as with cicadas), but many of these intervals have evolved from predator pressures which are not dependent on any distinct differences between gravitational waves from various sources, like mars or vespa. Gravitational waves are plausibly used by amphibians and bacteria as a timing mechanism to spawn , NOT because they inadvertently coincide with lunar/solar cycles as do human menstrual cycles, but because they depend on them lacking other stimulus.
A reasonable question might be: Why Gravitational perception? The same might be asked though of vision, hearing, or magnetic perception like Loggerhead turtles and some birds possess. The Sun & Moons gravity affects water, and biological organisms are mostly water. The traits survival mechanism would be to time a periodical flood of spawn so as to overwhelm any predators by suddenly presenting more offspring than predators could possibly consume. Thus insuring that some will survive but offering nothing between cycles so as to keep predator populations low.
Given the above, it's possible that intestinal organisms could also differ between individuals depending on the time of year they were first obtained. An experiment by Dr. Richard Blumberg of Harvard Univ. showed that mice who were borne in a sterile environment without bacteria of any kind, lacked immunity to certain infections. "Dr. Blumberg and his colleagues found that they could prevent the mice from becoming ill by giving them bacteria while they were still young. However acquiring a microbiome as an adult did not help the rodents."  Thus it's possible that whatever kinds of bacteria acquired when young, would be associated with a particular season. This microbiome is acquired through seasonal pollen, rain, dust, mold or whatever, and remains with a person to influence how they respond to changes in gravitation. Though they could just as well respond to other environmental factors. That kind of influence would have the same effect on people as the Astrological Signs, which are personality patterns also associated with seasons. And the variations of individual responses to gravitation could be explained by the differences in seasonal microbiome communities.
One possible test of this hypothesis might be to find women with irregular menstrual cycles and survey them for having been given antibiotics or some other medicine or food which disrupts intestinal flora as young children, probably before the age of one. I'm not about to do such a survey but if the data was already available, it would be interesting to look into it. Also Missing microbes: Antibiotic resistance at birth (wired.com).
1. Studies of the human microbiome yield new insights (NY Times)
2. Amphibians mate on full moon (bbc)
3. Triggers for Warm Water Coral Spawning "Scientists believe three factors trigger the spawning: water temperature, phase of the moon, and time of sunset. The water temperature in August or early September seems to be conducive to the spawning, although scientists don’t know how coral can sense that water temperature. For that matter, they don’t know how coral know the phase of the moon, although the day of the spawning is clearly related to that as well." It's unknown that Cold/Deep Water Coral corals spawn on a neap tide (like warm/shallow corals which take advantage of slowed current to allow spawn to be fertilized before being dispersed). that cause would be moot because Deep sea tides don't move as much as a shore tide.
4. Lunar reproductive cycles (Google)