EDITORIAL

Christmas: An Event Driven by our Hormones?

The importance of Christmas for our consciousness is demonstrated

in neologisms such as ‘feeling Christmassy’: our language has no

equivalent for other festive events such as Easter, wedding anniver-

saries, birthdays or divorce days. In addition, attempts to phase-

shift Christmas from its normal time frame (e.g. after a long period

of illness) have been ineffective. A lack of Christmas feelings has

also been described on occasions when the event is celebrated out-

side its normal spatial milieu (e.g. as an astronaut in space or a

shipwrecked person on remote culturally deprived islands) (1).

Therefore, I propose that the Christmas phenomenon is spatially

and temporally defined.

One of the major questions in neurobiology is to understand the

fundamental mechanisms by which neuroendocrine systems

co-ordinate biological rhythms on multiple, interacting time scales.

On time scales of seconds, intrinsic activity-dependent membrane

properties determine bursting behaviour; on time scales of minutes,

rhythms can arise from slow paracrine or autocrine mechanisms,

and, on a time scale of hours or days, molecular clocks are driven

by dynamic networks of transcription factor expression. Seasonal

rhythms are, by contrast, relatively poorly understood. Here,

I describe a working hypothesis that may shed light on the complex

neuroendocrine substrate of the circannual Christmas rhythm,

whose zenith is preceded by intense anticipatory locomotor activity,

which is characterised by hedonic hyperphagia and which is

succeeded by a phase of torpor.

I hypothesise that Christmas is a hormonally regulated, food-

entrainable circannual rhythm involving the hypothalamic-hypophy-

sial axis. Many of my neuroscience colleagues accept that our

sensations, feelings and thoughts are based on the activity of

neurones but that emotional and, indeed, all interesting and

important behaviours are all ultimately defined by neurohormones.

Taking this into account, the circannual Christmas rhythm may be

seen to comprise:

• An organisational phase

• An active phase of hormone release and positive feedback

• A behavioural climax

• Negative feedback

Organisation

The first organisational phase results in the activation of a group

of nerve cells provisionally located in a nucleus of the hypothala-

mus (as everything important is located in the hypothalamus) that,

for the purposes of this paper, we refer to as the Christmas vivify-

ing centre (CVC, Fig. 1). The CvC is clearly sexually dimorphic, and

shows remarkable plasticity, with its neurones apparently lying dor-

mant for approximately 11 months per year. We predict that spon-

taneous mutations or conditional knockouts of the genes expressed

in the CvC results in phenotypes that will enable us to identify the

gene products as endogenous nostalgesics. We anticipate that their

behavioural effects can be partially antagonised by the oral admin-

istration of mulled ethanol.

Interestingly, over the last 10 years or so, the start of the organ-

isational phase has been slowly but steadily phase advanced from

the classical Zeitgeber (Advent) to the beginning of October. Factors

triggering organisational activity include environmental signals such

as candle lights and Christmas trees; these signals activate the neu-

rones of the CvC to such an extent that it initially retrieves undif-

ferentiated old memories from the depths of consciousness in

futile, neglected areas of the brain such as the hippocampus. Olfac-

tory and acoustic signals can act synergistically with these photic

cues; their specific mixture and notoriety compress to the concrete

perception ‘it feels like Christmas’ (2) and initiates the second

phase, the activation of hormones. It should be noted, however,

some experts deny that the ‘Christmassy feeling’ even exists (3, 4).

Correspondence to: M. Ludwig, Centre for Integrative Physiology, University

of Edinburgh, George Square, Edinburgh EH8 9XD, UK (e-mail: mike.ludwig@

ed.ac.uk).1Based on Weber, W. Weihnachten, ein hormonal gesteuerter Wirkvorgang.

Naturwissenschafliche Rundschau 1986; 39, 165–167.

Journal ofNeuroendocrinology

No other event in the Christian calendar has such a deep impact on our behaviour as the

annual event called Christmas. Christmas is not just ‘Christmas Day’; indeed, it is a long devel-

opmental rhythm with a period of almost exactly 365 days. Here, I describe the neuronal and

hormonal changes and their effects on our behaviour during the preparation and the execution

of the event1.

doi: 10.1111/j.1365-2826.2011.02244.x

Journal of Neuroendocrinology 23, 1191–1193

ª 2011 The Author. Journal of Neuroendocrinology ª 2011 Blackwell Publishing Ltd

Journal of NeuroendocrinologyFrom Molecular to Translational Neurobiology

Hormone release

Depending on an individual’s threshold for Christmas cues, the neu-

roendocrine cells of the CvC start to synthesise Christmas-releasing

factor (ChRF), which is likely to be released at the median eminence

into the primary capillary plexus of the hypothalamic-hypophyseal

portal system. The portal system will translocate ChRH to the ade-

nohypophysis, where it triggers the release of other hormones. The

peripheral effects of these other hormones are currently unknown

and of little interest to neuroscientists generally, although these

hormones can without need of evidence be assumed to cross the

blood–brain barrier and induce specific behavioural and emotional

effects, as no doubt will be readily verified by intranasal application

into human subjects (‘dupes’) and published in high impact journals

with appropriately erratic standards of refereeing.

The release of these anterior pituitary hormones will result in an

increased feeling of self-worthiness and affect elementary behav-

iour strategies of ‘giving and taking’ in the context of group and

pair bonding. We propose to name one of these hormones ‘presti-

gon’; an elevated intracerebral concentration of prestigon will

enhance the propensity to buy consumer goods of any kind (we

note, but then ignore, the evidence that prestigon may in fact be

identical with oxytocin). Under normal conditions, this behaviour

would be expected by classical neuroeconomic theory to be con-

trolled by the understanding of our own financial limits and per-

sonal requirements. However, a second pituitary hormone, that we

name ‘emotionin’ stimulates festive anticipatory activity. However,

emotionin also decreases our threshold for buying and consumption

of goods and thereby boosts the release of prestigon. In a positive-

feedback manner, both hormones build up their effects, eventually

disinhibiting cognitive processes of assessment, perception and

expectations. The environment is prepared well for all of this in

advance; shopper’s Christmas paradises have sprung up everywhere

dictating the behaviour of the hormonally-driven shopping addict.

The addict is now entrained to adequate self-manifestation in the

tribe and the high consumer demand of our society (5).

Climax

In general, this culminates on Christmas Eve or Christmas Day

(dependent on your nationality) with the act of giving Christmas pre-

sents. The ‘love hormone’ oxytocin induces feelings such as trust and

generosity (6,7) and sights such as mistletoes activate the hormone

kisspeptin, triggering a cascade of biochemical changes and a recapit-

ulation of pubertal behaviors (8). Understandably, thoughts such as ‘I

give you something – what do you give me?’ trigger high expectations

in every member of the tribe. The high levels of emotionin initially

prevent frustration-induced discord as a result of unfulfilled wishes.

Negative feedback

At the zenith of the circannual rhythm, various adverse side effects

emerge that may be attributed to excess intracerebral levels of

prestigon, which functionally antagonise satiety signaling. Feeding

and drinking behaviours persist, disconnected from all cognitive

restraint or sensory modulation. With the dysfunction of the

normal homeostatic mechanisms, oppressive feelings of corporeal

discomfort develop (9). We suspect that this triggers the release of

a hormone from the gastrointestinal tract, which we provisionally

call ‘gluttirin’. Gluttirin rapidly inactivates the effects of the Christ-

mas hormones by negative feedback at the level of the hypothala-

mus, resulting in an abrupt degradation of ‘Christmas craving’.

Disappointment over unfulfilled expectations or inappropriate gifts

(socks or ties) results in reciprocal conspecific or familial aggression.

These conflicts are exacerbated by inappropriate territorial behav-

iour resulting from dislocated relatives and former friends. Fortu-

nately, this phase is rapidly replaced by an extended torpor

associated with emotional desensitisation and sensory withdrawal.

Ultimately, the experience is sufficiently traumatic that sensible

plans are made to do everything different for next year and to

negotiate a multilateral reduction in the extent to which behaviour

becomes misaligned. This may be good thinking and a willful intent;

however, it is inevitable that, once again, we will again totally sur-

render to the effects of our Christmas hormones.

Declaration of competing interests

The author declares that he has no interest in receiving woollen

items next Christmas.

Acknowledgements

I thank Professor G. Leng and Dr Sutherland Maciver (Edinburgh) for airing

some of their unpublished observations.

Hippocampus

Hypothalamus

CvC

Oxytocin

Emotionin

Prestigon

Pituitary gland

ChRF

Fig. 1. Schematic presentation of the hormones released during Christmas.

ChRF, Christmas-releasing factor; CvC, Christmas vivifying centre.

1192 Editorial

ª 2011 The Author. Journal of Neuroendocrinology ª 2011 Blackwell Publishing Ltd, Journal of Neuroendocrinology, 23, 1191–1193

Received 12 September 2011,

Revised 14 October 2011,

accepted 15 October 2011

M. Ludwig

Centre for Integrative Physiology,

University of Edinburgh,

Edinburgh, UK.

References

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3 Dr Seuss . How the Grinch Stole Christmas. New York, NY: Harper Collins

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4 Kaye M. The Last Christmas of Ebenezer Scrooge. Holicong, PA: Wildside

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5 Olsen CM Natural rewards, neuroplasticity, and non-drug addictions. Neu-

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9 Hairon N. How Christmas festivities and pressure can damage health and

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Editorial 1193

ª 2011 The Author. Journal of Neuroendocrinology ª 2011 Blackwell Publishing Ltd, Journal of Neuroendocrinology, 23, 1191–1193