I just came across an interesting study on the effects of restricting water. The study only involved rats, so to whatever level this is translatable to us humans: water restriction results in increased bodily stress factors and increased psychological unrest.
It might be nothing more than intuition confirmed, but I always appreciate it when that happens. 
There’s not much more info available than that, but the takeaway is… DRINK WATER!!
Have any of you all ever self-experimented (whether accidentally or not) and noticed different effects of water restriction/dehydration? I know I have but never rigorously thought about the cause and effect… I’ll think about it more now.
here’s the study abstract:
Zhu ZH, Wang BR, Tan QR, Duan XL, Kuang F, Xu Z, Ju G.
Effects of water restrictions on the physiological parameters, psychological
behavior and brain c-Fos expression in rats.
Neurosci Bull. 2006 May;22(3):144-50.
PMID: 17704842
Objective In order to characterize the feature of stress response induced by
stressor with both physical and psychological natures, the effects of water
restriction performed in different experimental modes on the physiological
parameters, psychological behavioral manifestations and brain c-Fos
expressions were observed and compared.
Methods Fifty-eight male Wistar rats were used and randomly divided into
three experimental groups (n = 18 for each) and a control group (n = 4). In
control group, the rats were allowed to access drinking water freely at all
experimental period. In the experimental groups the water supply to the rats
was restricted. In timed water supply (TW) group, the water was supplied
twice a day, 10 min for each in fixed hours every day. In empty
bottle-served (EB) and water-restricted (WR) groups, the water was served
only once a day for 10 min, either in the early morning or evening, and in
the other time point scheduled for water supply only an empty bottle without
water was provided in the EB group and nothing was given in the WR group.
The quantities of drank water and eaten food, weight-gaining, and behavior
score were observed every day. The serum level of corticosterone was assayed
and the rats were sacrificed with fixative perfusion of 3 d, 7 d or 14 d,
respectively, following water restriction (n = 6 for each time point in each
group). The brain c-Fos expressions were examined with immunohistochemical
method.
Results The slow down of weight-gaining, rise of serum corticosterone level,
occurrence of psychological behavioral manifestations of unpeaceful
restlessness such as exploring and attacking, enhance of c-Fos expression in
the subfornical organ (SFO), median preoptic nucleus (MnPO), area postrema
(AP), hypothalamic paraventricular nucleus (PVN), supraoptic nucleus (SON),
medial (MeA) and central (CeA) amygdaloid nucleus and ventrolateral septum
(LSV) were noticed in both EB and WR groups, except the nucleus of solitary
tract (NTS) in which the Fos expression was decreased. The changes of Fos
expression in most of nuclei in EB group began at day 3, at least persisted
till day 7, and backed down at day 14, while in WR group, similar changes
started at day 7 and reached its peak at day 14. In TW group, only the
concentration of corticosterone at day 7 was slightly increased and the rest
indexes observed were unchanged.
Conclusion The results indicate that water restriction induces physical as
well as psychological stress responses. And the water restrictions
experimentally executed in different modes result in different
manifestations of behavioral response and brain immediately early gene
expression in discrete brain nuclei/regions.