E-Letter responses to:

reports: Stéphanie Maret, Paul Franken, Yves Dauvilliers, Norbert B. Ghyselinck, Pierre Chambon, and Mehdi Tafti Retinoic Acid Signaling Affects Cortical Synchrony During Sleep Science 2005; 310: 111-113 [Abstract] [Full text] [PDF]

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Published E-Letter responses:

Re: Retinoids and sleep in humans

Mehdi Tafti   (16 November 2005)

Retinoids and sleep in humans

Maurice A.M. van Steensel   (8 November 2005)

Re: Retinoids and sleep in humans 16 November 2005
Mehdi Tafti CIG, Lausanne University Respond to this E-Letter: Re: Re: Retinoids and sleep in humans	As reported in our paper, in our original screening of the six most common inbred mouse strains, we found only one (DBA/2J) with a dramatic change in delta activity in sleep. Therefore, decreased delta activity is not common, and if a similar phenotype occurs in humans, then only a small number may be found. Consequently, retinoic acid use in humans may not affect sleep and/or induce depression in all subjects but in those susceptible because of a change in Rarb gene expression. Epidemiological screening of patients with acne and treated with retinoic acid derivatives should help indentifying those with sleep problems that can then be evaluated for Rarb gene polymorphisms and sleep EEG.
Retinoids and sleep in humans 8 November 2005
Maurice A.M. van Steensel, Dermatologist University Hospital Maastricht, the Netherlands, dept of Dermatology Respond to this E-Letter: Re: Retinoids and sleep in humans	It was with considerable interest that I read the paper by Maret et al. in which they show that the RARB gene can influence cortical synchronization during sleep in mice. It seems reasonable to assume that retinoic acid may influence the same process, and by extension, the need for sleep in humans. It would be of great interest to determine whether this is true. Meanwhile, the extensive clinical use of retinoic acid derivatives in dermatology presents us with a convenient model system. Patients are treated with pharmacological doses of potent retinoic acid derivatives. If retinoic acid signaling is indeed important for the regulation of sleep in humans, as might be implied from the Maret et al. paper, one might expect patients treated with retinoids to suffer from sleep disturbances. From my own observations in patients treated with isotretinoin and acitretin for various skin conditions such as acne and congenital disorders of keratinization it would appear, however, that no overt sleep disturbances occur. It has been suggested that the use of isotretinoin is associated with depression and suicidal tendencies (1), which might conceivably be linked to disturbances in cortical synchronization during sleep. Recent data however seem to indicate that there is no such effect (2). In conclusion, while retinoic acid might in one inbred mouse strain be involved in the regulation of sleep, its contribution to said process and others that might depend on cortical synchronization in humans may be minor. A systematic survey and perhaps systematic EEG examination of patients taking oral retinoids should settle the matter. References 1. Hull and D'Arcy, Am. J. Clin. Dermatol. 4 (no. 7), 493-505 (2003). 2. Marqueling and Zane, Semin. Cutan. Med. Surg. 24 (no. 2), 92-102 (2005).