It will do, but it does not sound very good.
'An increasing trend'/'a decreasing trend' might be better.
Better still would be to avoid 'showed' and 'trend' altogether, and write 'increased' and 'decreased', but this implies a stronger relationship than you need for 'trend'.
Are you sure 'light cycle' and 'dark cycle' are correct, that they are two different cycles, not two parts (phases, perhaps) of the same cycle?
Thanks for your reply.
You mean "trend" isn't a fine word in this context? Isn't there any other word that convey the same meaning?
Light cycle is from 7:00 am to 7:00 pm and dark cycle from 7:00 pm to 7:00 am.
"Liver lipid peroxidation exhibited a tendency to increase during the light phase, and to decrease during the dark phase."
I find scientific language prefers "exhibit" over the more colloquial "show".
As Uncle Jack suggests, a "cycle" is usually the entirety of what is repeated, with its parts called "phases".
The moon goes through one cycle every month, which includes several phases: new moon, first quarter, full moon, last quarter...
Trend is fine (Cenzontle's 'tendency' is probably better though), but suggests some imprecision and variation. In an 'increasing trend', you can expect there to be times when whatever it is that trends to actually decrease for short periods between longer/steeper periods of increasing. If your data doesn't show this variation, then 'trend' may be unnecessary, and merely makes it harder to read.
Your light/dark cycle must be common enough in experiments of this kind. 'Light cycle' and 'dark cycle' sound wrong to me, but it isn't my field, so if other experimenters use these terms then this is probably how they are used, but I would have thought light and dark to be two parts of one 24-hour cycle. [cross-posted]