This work was carried out at the Institute of Biomedicine, Department of Physiology, University of Helsinki. I wish to express my gratitude to the Chairmen of the Institute: Professor Olli Jänne and Professor Ismo Virtanen, and the Department Head, Professor Dag Stenberg for placing the facilities of the Department at my disposal.

    I am deeply grateful to the supervisors of this work: Professor Dag Stenberg and Docent Tarja Porkka-Heiskanen for their unfailing interest, guidance and support during the progress of this work and the facilities to carry  it out. I wish to thank my colleagues in the research group: Lauri Alanko M.D., Marjut Asikainen M.D. and Pia Niittymäki M.B. for their collaboration and support. I wish also thank Ms. Sari Levo-Siitari for her invaluable help in experimental animal and in situ hybridization work.

    I am grateful to the reviewers of this manuscript: Professor Juhani Leppäluoto and Professor Leena Rechardt for their valuable comments and constructive criticism.

    I wish to express my deepest thanks to all the personnel of the Department of Physiology,  especially to Ms. Anne Nenonen for secretarial assistance, Ms. Seija Turunen and Ms. Nina Katajamäki for their assistance in collecting the literature, Ms. Kaija Hakkarainen for the experimental animal care and Docent Ilkka Linnankoski and Dr. Ernst Mecke for the revision of the English language of the manuscript.

    I wish to express my gratitude to the collaboration laboratories: Professor Fred W. Turek  and his group, especially Ms. Yi-Rong Ge in the Department of Neurobiology and Physiology at Northwestern University, Evanston, IL, U.S.A., and  Professor Irene Tobler and her group at the Institute of Pharmacology, University of Zürich, Switzerland.

    I owe my deepest thanks to my parents Maija-Liisa and Antti, sister Sanna and brother Ville,

and all of my relatives and friends, especially the crews of s/y Brainstorm, s/y Marleena and s/y Jasmiina, for their continuous encouragement, interest and support during the progress of this work.

    For the financial support I wish express my thanks to the Finska Läkaresällskapet, the Paulo Foundation, and the Finnish Sleep Research Society.

Helsinki, September 1999

Jussi Toppila