Any tidal effect would be because we have mass, not because we are largely water.

Pro. When isolated from external influences of daylight, etc., in caves, humans tend to have a daily cycle of nearer 25 than 24 hours. This is closer to the cycle of the Moon passing overhead than actual daylength. No-one in my knowledge has thought that a tidal explanation for this is likely.

Con. Research in a major hospital in South Wales has shown no link between childbirth and the state of the tide. My feeling about this is that any result would be more likely to show up in old data, before mothers were all in hospitals where interventions may be designed to encourage birth at convenient hours.

Pro. Clams (and other sea creatures) which have behaviours related to tides, have been observed to change the times of opening etc. to match what would be the local tides when removed from the coast to laboratories far removed from coasts. This was in the States, so far removed means several hours in Moon time.

Con. Humans, and even more clams, have masses so small that the effect of gravity changes would be minimal.

Pro. Tidal cycles show up on gravity meters which are less massive than humans. The Moon's pull also affects the rock beneath, so altitude changes. If near the coast, the tidal loading on the seabed has an effect. Whether these tiny changes can be detected by people is questionable - but if people can dowse, maybe...?

Con. Behaviours attributed to lunar changes are usually monthly, and probably related to the light enabling people to be out and about rather than daily, as a tidal effect would be. Any changes based on the lunar cycle would probably be drowned out by other effects in daily life.

To study tidal effects you would need to keep your subjects isolated from every signal except gravity - continuous light, no radio or TV, food continuously available - over a very long period. Or access the results from the cave experiments and relate them to lunar positions at the place and time of the experiment.

Penny